Electric Machine and Manufacturing  Process for Same

ABSTRACT

To provide an electric machine capable of being improved in both fabricability and reliability, and a process for manufacturing the machine. 
     In order to ensure resolution of the above subject, a stator coil  112  is constructed from a plurality of coil conductors  113  each mounted in two spaced slots  111   b , each of the coil conductors  113  is formed under a no-end state at any portions from a connection  113   j  to a connection  113   k , and a crossover-side coil end  113   c  that includes crossover side portions  113   e  and  113   f  crossing over from one of two spaced slots  111   b  to the other of the slots, guided from an end of a stator core  111  outside the outside of the stator core, and extending in the direction that the crossover side portion is away from the end of the stator core  111  is formed so that an angle of a crossover side of the crossover side portion  113   e  with respect to an edge present at the end of the stator core  111  is greater than an angle of a crossover side of the crossover side portion  113   f  with respect to the edge present at the end of the stator core  111.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric machine and a manufacturingprocess for the same, and typically, to a technique for improvingfabricability and reliability of an electric machine having a winding.

2. Description of the Related Art

Known existing techniques relating to an electric machine with a windingare disclosed in JP-A-2001-298888 or JP-A-2001-37131, for example.

JP-A-2001-298888 discloses a technique for constructing a stator coil ofan alternating-current power generator for a motor vehicle by using aU-shaped segment coil.

JP-A-2001-37131 discloses a technique for constructing a stator coil ofan alternating-current power generator for a motor vehicle by using acoil piece that includes a first rectilinear portion, a secondrectilinear portion connected to the first rectilinear portion via asingle bend, and a third rectilinear portion connected to the secondrectilinear portion via a single bend and parallel to the firstrectilinear portion.

SUMMARY OF THE INVENTION

For example, as with the stator coil disclosed in JP-A-2001-298888 orJP-A-2001-37131, a winding provided in an electric machine isconstructed to be first guided from both ends of a multi-slotted coreoutward to an external section of the core and then mounted in twospaced slots in such a form as to cross over the slots. Physicaldimensions of the electric machine having the thus-constructed windingare influenced by height of the winding end which has been guided fromthe ends of the core outward to the core exterior (i.e., influenced bylength of the winding in the direction that the winding is away from theends of the core). For this reason, an increase in the height of thewinding end increases the physical dimensions of the electric machine.

In recent years, electric machines have been required to be miniaturizedfor purposes such as narrowing the space needed to mount the electricmachine in a structure (e.g., for such vehicle alternating-current powergenerator as disclosed in JP-A-2001-298888 or JP-A-2001-37131, anautomobile), or reducing costs of the electric machine.

One possible method for miniaturizing an electric machine having theabove-constructed winding is by reducing the end of the winding inheight. Reduction in the height of the winding end would be achievableby disposing, adjacently to an end of a core, a bend provided at thewinding end so as to cross over two spaced slots, and dimensionallyreducing a section that ranges from the end of the core to the bend. Ifthe bend at the winding end is disposed adjacently to the end of thecore, however, the bend (twisted portion) at the winding end easilycomes into point contact with a corner of the core. This is consideredto reduce performance of electrical insulation provided at the bend(twisted portion) of the winding end.

For a winding constructed using a U-shaped segment coil, as in thetechnique that JP-A-2001-298888 discloses, two bends (twisted portions)formed in the U-shaped segment coil are considered to easily come intopoint contact with each other when the winding is mounted around a core.When the winding constructed using a U-shaped segment coil is mountedaround the core, therefore, it is very important to manage properly thetwo bends formed in the U-shaped segment coil. However, the two bendsdisposed at inside-diametral and outside-diametral sides of the core aredifficult to manage at the same time. In addition, the bend disposed atthe inside-diametral side of the core is difficult to manage as well asto view from the outside-diametral side of the core. Consequently, thewinding constructed using a U-shaped segment coil, as in the techniqueof JP-A-2001-298888, is considered to decrease in working efficiency ofthe mounting operation for the winding.

Additionally, for a winding constructed by connecting different ends ofa coil piece (i.e., half-coil) whose rectilinear portions are eachinterconnected via a single bend, as in the technique thatJP-A-2001-37131 discloses, it is considered to be difficult, when thewinding is mounted around a core, to cause the bend in the coil piece tocome into point contact. However, for the winding constructed with thecoil piece connected at ends thereof, it is necessary that insertion ofthe coil piece into slots of the core and the connection of the coilpiece at the ends thereof should be conducted at both ends of the core.Accordingly, mounting the winding around the core requires a largenumber of man-hours. Consequently, the winding constructed by connectingthe ends of the coil piece (half-coil) whose rectilinear portions areeach interconnected via a single bend, as in the technique ofJP-A-2001-37131, is considered to decrease in working efficiency of themounting operation for the winding.

The present invention provides, as a typical aspect thereof, an electricmachine capable of being improved in both fabricability and reliability,and a process for manufacturing the machine.

More specifically, in a typical aspect of the present invention, awinding mounted around a core which has a plurality of slots isconstructed from a plurality of unit windings mounted in two slotsspaced from each other, each of the unit windings is formed under ano-end state at any portions from one of two ends to the other end, anda crossover-side conductor end of the unit winding that has twoconductor lead-out portions, each of the conductor lead-out portionsbeing adapted to cross over one of the two spaced slots through theother slot, to be guided from an end of the core outward to an externalportion of each of the two slots, and to extend in a direction that theconductor lead-out portion is away from the end of the core, is formedsuch that an angle of the crossover side of one of the two conductorlead-out portions with respect to an edge of the core is greater than anangle of the crossover side of the other conductor lead-out portion.

The no-end state here denotes a connectionless state and indicates thatthe unit winding is formed of a succession of winding conductors.

According to the foregoing typical aspect of the present invention, theplurality of unit windings can be inserted from one end of the core intothe plurality of slots thereof and since the plurality of unit windingscan be connected at the other end of the core, mounting the windingsaround the core does not require a large number of man-hours. Inaddition, according to the foregoing typical aspect of the presentinvention, point contact between the core and one of the two conductorlead-out portions at the crossover-side conductor end can be made lessprone to occur when the windings are mounted around the core, andappropriate mounting of the windings around the core can be achievedjust by managing point contact between the core and one of the twoconductor lead-out portions at the crossover-side conductor end.According to the foregoing typical aspect of the present invention,therefore, since an increase in the number of man-hours required for themounting of the windings around the core can be suppressed and sincepoint contact of the windings with respect to the core can be easilymanaged, it is possible to improve mounting efficiency of each winding,to suppress decreases in performance of the electrical insulation on theunit winding due to point contact between the core and the bend (twistedportion) in the winding, and hence to improve the performance of theelectrical insulation on the winding.

According to a typical aspect of the present invention, bothfabricability and reliability of an electric machine can be improvedsince a winding can be improved in mountability and in performance ofelectrical insulation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a first embodiment of the present invention,and is also a block diagram showing a total system configuration of adriving system mounted in a four-wheel drive vehicle;

FIG. 2 is a block diagram showing an electrical system configuration ofa follower driving system mounted in the four-wheel drive vehicle ofFIG. 1;

FIG. 3 is a sectional view showing an internal configuration of a motorwhich forms part of the follower driving system of FIG. 2;

FIG. 4 is an enlarged view that shows one axial end of a stator corewhich forms part of the motor of FIG. 3, and is an enlarged plan viewshowing a crossover-side coil end of a coil conductor;

FIGS. 5A to 5D are plan views showing partly in perspective form aconfiguration of the coil conductor of FIG. 4 and the steps of formingthe coil conductor;

FIG. 6 is a plan view showing a configuration with a plurality of coilconductors mounted on the stator core of FIG. 4;

FIG. 7 is a plan view showing a moving state of the coil conductor ofFIG. 4 during forming of a connecting-side coil end of the coilconductor;

FIG. 8A are diagrams showing stator coil configuration andelectromagnetic noise characteristics of the motor of FIG. 3, being aplan view showing the crossover-side coil end of the coil conductor anda characteristics diagram showing a relationship of a noise level(plotted on a vertical axis) with respect to speed (plotted on ahorizontal axis), respectively;

FIG. 8B are diagrams showing stator coil configuration andelectromagnetic noise characteristics in a comparative example, being aplan view showing the crossover-side coil end of the coil conductor anda characteristics diagram showing a relationship of a noise level(plotted on a vertical axis) with respect to speed (plotted on ahorizontal axis), respectively;

FIGS. 9A to 9D are diagrams showing a second embodiment of the presentinvention, and is also a plan view showing partly in perspective form aconfiguration of and forming steps for a coil conductor mounted on astator core of a motor;

FIG. 10 is a plan view showing a configuration with a plurality of coilconductors mounted on the stator core of FIG. 9; and

FIG. 11 is a plan view showing a moving state of the coil conductor ofFIG. 9 during forming of a connecting-side coil end of the coilconductor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in accordancewith the accompanying drawings.

An example in which a configuration of and a manufacturing process foran electric machine of the present invention are applied to aconfiguration of and a manufacturing process for an electric motor fordriving a vehicle will be described in one embodiment below.

In another embodiment below, a field-winding-type synchronous motor willbe described as an example of the motor for driving a vehicle.

In addition, in either of the above two embodiments, a four-wheel drivehybrid electric vehicle that uses an internal combustion engine to driveone of two pairs of front or rear wheels and uses an electric motor todrive the other pair of wheels, more particularly, a four-wheel drivehybrid electric vehicle without a battery for driving an electric motorwill be described as an example of a vehicle in which the motor fordriving a vehicle is mounted.

The configuration described hereunder can also be applied to otherrotary electric machines for a vehicle, such as: a vehicle-mountedauxiliary electric machine, an electric machine for starting an internalcombustion engine, and a power generator for a vehicle power supply.

Additionally, the motor for driving a vehicle can be of apermanent-magnet type synchronous motor or of an induction machine.

Furthermore, the automobile in which the motor for driving a vehicle ismounted can be either: a four-wheel drive hybrid electric vehicle havinga motor-driving battery instead of the foregoing dedicated powergenerator for driving an electric motor; a purely electric vehicle witha vehicle-driving electric motor as the only driving source for avehicle; or a hybrid electric vehicle having a vehicle-driving electricmotor and an internal combustion engine as driving sources for a vehicleand using either driving source to drive one of two pairs of front orrear wheels.

Moreover, the configuration described hereunder can also be applied torotary electric machines in addition to automobiles, such as: anelectric motor for driving a train, and a rotary electric machine forindustrial equipment (e.g., equipment for driving industrial devicessuch as pumps, and equipment for driving production devices installed ata factory).

Moreover, the configuration described hereunder can be applied to linearmotors as well as to rotary electric machines. The linear motors eachinclude a stator and a movable element disposed opposedly to the statorand movable by a magnetic interaction with the stator. The statorincludes a core extending rectilinearly and having a plurality of slots,and a winding constructed by electrically interconnecting a plurality ofcoil conductors each mounted in two spaced slots. The movable elementrectilinearly moves along an opposed surface with respect to the statorby magnetic attraction and repulsion with respect to the stator.

First Embodiment

A first embodiment of the present invention will be described inaccordance with FIGS. 1 to 8.

First, a driving system configuration of a four-wheel drive hybridelectric vehicle without a motor-driving battery is described belowusing FIG. 1.

In FIG. 1, a control cable for transmitting control signals is shownwith a thin solid line, and an electrical cable for supplying electricalenergy is shown with a solid line thicker than the solid line denotingthe control cable. These also apply to FIG. 2 described later herein.

The four-wheel drive hybrid electric vehicle without a motor-drivingbattery (four-wheel drive vehicle 1) is a composite drive vehicle thatincludes a driving system based on an internal combustion engine 6, anda driving system based on a motor 100 which is a rotary electricmachine. The vehicle activates the engine 6 to drive front wheels 2(main wheels) and activates the motor 100 to drive rear wheels 4(follower wheels). The engine 6 is a motive power source constituting amain driving system for the front wheels 2, and uses thermal energy togenerate rotational motive power in all traveling speed regions of thevehicle. The motor 100 is a motive power source constituting a followerdriving system for the rear wheels 4, and uses electrical energy togenerate rotational driving force during a time interval from a start ofthe vehicle to an arrival at a traveling speed region depending onlyupon power of the engine 6. The motor 100 also generates rotationaldriving force if, while the front wheels 2 are being driven by theengine 6, front wheel slipping on an ice-covered road or other travelingroads that reduce a road surface friction coefficient μ occurs andthereby the engine 6 cannot transmit the power thereof to the roadsurface.

Although using the engine 6 and the motor 100 to drive the front wheels2 and the rear wheels 4, respectively, is taken by way of example in thedescription of the present embodiment, the system may be constructed sothat the engine 6 and the motor 100 drive the rear wheels 4 and thefront wheels 2, respectively.

After being gear-changed by an automatic transmission 7, rotationalmotive power of the engine 6 is transmitted to left and drive shafts 3of the front wheels 2 via a power transmission mechanism 8. The frontwheels 2 are thus driven by the engine 6 in the entire traveling speedrange of the vehicle.

An electric power generator 9 for auxiliary devices mounted in thevehicle, and a dedicated electric power generator 200 for driving aremechanically coupled to the engine 6 via a belt. Both power generatorsare actuated by the rotational motive power of the engine 6, and eachgenerator generates electric power for a specific purpose.

The power generator 9 for the vehicle-mounted auxiliary devicesconstitutes a 14-volt power supply mounted in the vehicle, and generatesdirect-current (DC) power for recharging the vehicle-mounted battery 10whose nominal output voltage is 12 volts. The power generator 9 for theauxiliary devices also generates DC power for driving thevehicle-mounted auxiliary devices.

The dedicated power generator 200 for driving constitutes a motor powersupply for generating dedicated driving power for the motor 100. Also,the dedicated power generator 200 for driving constitutes a 42-voltpower supply mounted in the vehicle, the generator 200 being capable ofgenerating power higher than that of the power generator 9 for thevehicle-mounted auxiliary devices. The generator 200 can generate avariable output voltage ranging from 0 volts to 50 or 60 volts,depending on the driving force required of the motor 100.

An example in which the dedicated power generator 200 for driving isequipped as the power supply for the motor 100 is described in thepresent embodiment. In this example, a dedicated large-capacity batteryfor motor driving is unnecessary, and accordingly a mounting space forthe follower driving system of the follower drive wheels (in the presentembodiment, the rear wheels 4) can be reduced and the follower drivingsystem for the follower drive wheels can be supplied at an inexpensiveprice, compared with the follower driving system of a mechanicalfour-wheel drive vehicle which uses engine power to drive front and rearwheels.

In addition, in the present embodiment, the motor 100 is driven with thedriving-dedicated power generator 200 as its power supply at a lowvoltage level and a high current level, so it is possible to obtain ahigh torque output required in the traveling performance of the vehicle,and hence to supply a follower driving system substantially equivalentto that of the mechanical four-wheel drive vehicle which uses enginepower to drive front and rear wheels.

The vehicle-mounted auxiliary power generator 9 and the dedicated powergenerator 200 for driving are arranged inside the engine room togetherwith the engine 6. Since the dedicated power generator 200 for drivingis a water-cooled enclosed rotary electric machine and since thevehicle-mounted auxiliary power generator 9 is an air-cooled open rotaryelectric machine, a position at which the power generator 200 isinstalled with respect to the engine 6 can be lower than a position ofthe power generator 9 is installed with respect to the engine 6.

As described above, a battery for motor driving is absent in the presentembodiment. The DC power that has been output from the dedicated powergenerator 200 for driving, therefore, is input directly to a DC side ofan inverter unit 400 via a relay 300. The inverter unit 400 converts theinput DC power into three-phase AC power required for the driving of themotor 100, and supplies the thus-obtained three-phase AC power to themotor 100. The motor 100 then operates on the three-phase AC power, thusgenerating the rotational motive power necessary to drive the rearwheels 4.

Rotational power from the motor 100 is transmitted to left and rightdrive shafts 5 of the rear wheels 4 via a clutch 500 connected to anoutput end of the motor 100, and a differential gear 600 connected to anoutput end of the clutch 500. Thus, the rear wheels 4 are driven byusing the rotational motive power of the motor 100 during the timeinterval from the start of the vehicle to the arrival thereof at atraveling speed region depending only upon power of the engine 6. Forthe same reason, the rear wheels 4 are also driven if, while the frontwheels 2 are being driven by the engine 6, front wheel slipping on anice-covered road or other traveling roads that reduce the road surfacefriction coefficient μ occurs and the engine 6 cannot transmit the powerthereof to the road surface. The follower driving system in the presentembodiment, therefore, allows the vehicle to be started and run at hightorque while the vehicle is stabilized, and even if the front wheels 2slip, immediately makes the front wheels grip the road surface so thatthe vehicle can be stably and reliably run on the traveling road of asmall friction coefficient μ.

The differential gear 600 is a power transmission mechanism fordistributing the rotational motive power of the motor 100 to the leftand right drive shafts 5, and has an integrated set of reduction gearsfor reducing the rotational motive power of the motor 100.

The motor 100 and the inverter unit 400 are arranged adjacently to eachother, and both are installed in a narrow underfloor space ranging froma rear seat of the vehicle to a trunk room and neighboring thedifferential gear 600.

While an example in which the motor 100 and the inverter unit 400 arearranged separately from each other is taken in the description of thepresent embodiment, both may be formed into a mechanically andelectrically integrated unit. In this case, miniaturization of thedevices and improvement of their mountability in the vehicle can beachieved.

Alternatively, the motor 100 may be integrated with the clutch 500 andthe differential gear 600.

The clutch 500 is an electromagnetic power cutoff mechanism thatcontrols motive power transmission by controlling two clutch plates bymeans of electromagnetic force. During the time interval from the startof the vehicle to the arrival thereof at a traveling speed regiondepending only upon the power of the engine 6, and in up to a maximumtraveling speed region that permits the rear wheels 4 to be driven bythe rotational motive power of the motor 100, if the front wheels 2driven by the engine 6 slip on an ice-covered road or other travelingroads that reduce the road surface friction coefficient μ and the powerof the engine 6 cannot be transmitted to the road surface, the clutch500 is controlled motive power transmission to engage the two clutchplates and transmit the rotational power of the motor 100 to thedifferential gear 600. When the vehicle is in the traveling speed regiondepending only upon the power of the engine 6, motive power transmissionis controlled to disengage the two clutch plates and cut off thetransmission of the rotational power from the motor 100 to thedifferential gear 600.

Operation of the devices constituting the follower driving system of therear wheels 4 is controlled by signals or electric power supplied froman electronic circuit unit 700. The electronic circuit unit 700 has aplurality of control circuit boards. A microcomputer for executingpreprogrammed arithmetic operations required for control of each device,a storage memory in which the programs required for the arithmeticoperations in the microcomputer, maps, parameters, and other data areprestored, integrated circuits (ICs) formed by integrating resistors andother circuit elements, and a plurality of other electronic componentsare mounted on each control circuit board. These control circuit boardsconstitute a four-wheel driving controller, a motor controller, andchopper circuits. These constituent elements of each control board willbe described later herein.

The kinds of control that the electronic circuit unit 700 undertakesinclude: field control that controls the generation of electric power inthe driving-dedicated power generator 200 by controlling a field currentsupplied thereto; relay control that controls electrical connectionbetween the driving-dedicated power generator 200 and the inverter unit400 by controlling contact point driving of the relay 300; drivingcontrol that controls the driving of the motor 100 by controllingelectric power conversion by the inverter unit 400; field control thatcontrols the driving of the motor 100 by controlling a field currentsupplied thereto; and clutch control that controls the engagement anddisengagement of the clutch 500 by controlling a field current suppliedthereto.

Each device constituting the follower driving system of the rear wheels4, and the electronic circuit unit 700 are electrically connected via asignal cable or an electrical cable. The vehicle-mounted battery 10 andthe electronic circuit unit 700 are electrically connected via anelectrical cable. Engine components (an air throttle valve, intake andexhaust valves, and a fuel injection valve), an engine control unit thatcontrols, in addition to operation of a gear-shifting mechanismconstituting the automatic transmission 7, operation of the powergenerator 9 for the vehicle-mounted auxiliary devices, an anti-lockbrake system controller that controls operation of a caliper cylindermechanism constituting an anti-lock brake system, and othervehicle-mounted controllers (not shown) are electrically connected tothe electronic circuit unit 700 via a local area network (LAN) cable.Thus, the vehicle-mounted controllers can share information that eachthereof possesses, and the electronic circuit unit 700 can acquire anengine speed signal, a shift lever position signal, an acceleratoropening angle signal, and a brake stroke signal, from the engine controlunit. The electronic circuit unit 700 can also acquire a wheel velocitysignal from the anti-lock brake system. The electronic circuit unit 700can acquire these signals as input information when necessary, and canuse the acquired input information to conduct each kind of controloutlined above.

An example in which the engine control unit controls the operation ofthe gear-shifting mechanism constituting the automatic transmission 7 isdescribed in the present embodiment. If the vehicle has a gear shiftcontrol unit, the operation of the gear-shifting mechanism constitutingthe automatic transmission 7 is controlled by the gear shift controlunit. In this case, the shift lever position signal input to theelectronic circuit unit 700 will be acquired from the gear shift controlunit via the LAN cable.

Next, a configuration of the follower driving system for the rear wheels4 is described in detail below using FIG. 2.

The relay 300 and the clutch 500 are omitted from FIG. 2.

The electronic circuit unit 700 includes the four-wheel drivingcontroller 710, the motor controller 720, and the chopper circuits 730,740.

Although an example in which the four-wheel driving controller 710, themotor controller 720, and the chopper circuits 730, 740 are integratedinto one electronic circuit unit 700 is described in the presentembodiment, the constituent elements of the electronic circuit unit 700may each be a separate structure. Alternatively, only the four-wheeldriving controller 710 may be constructed separately and the remainingconstituent elements integrated into one unit.

An example in which the electronic circuit unit 700 is providedseparately from the motor 100 and the inverter unit 400 is alsodescribed in the present embodiment. To construct the motor 100 and theinverter unit 400 into a mechanically and electrically integrated unit,the electronic circuit unit 700 may be integrally incorporated into theintegrated unit. In this case, the four-wheel driving controller 710 maybe built together with the motor controller 720 and the chopper circuits730, 740 into the unit or only the four-wheel driving controller 710 maybe provided separately outside the unit. Otherwise, the motor controller720 may be assembled into the inverter unit 400, the chopper circuit 730into the clutch 500, and/or the chopper circuit 740 into the motor 100.

The four-wheel driving controller 710 acquires, as input information,the shift lever position signal and accelerator opening angle signaloutput from the engine control unit 11, and the wheel velocity signaloutput from the anti-lock brake system controller. On the basis of theinput information, the four-wheel driving controller 710 outputs a motortorque target data signal as output information to the motor controller720. On the basis of the input information, the four-wheel drivingcontroller 710 also outputs a clutch control command signal for drivingthe clutch 500, to the chopper circuit 730, and a relay control commandsignal for driving the relay 300, to a driver circuit of the relay 300,as output information.

The motor controller 720 acquires, as input information, the motortorque target data signal output from the four-wheel driving controller710, the engine speed signal output from the engine control unit 11, anda motor armature current signal, motor field current signal, motor speedsignal, and capacitor voltage signal (inverter input voltage signal)output from later-described sensors 140 and 440. On the basis of thesesignals, the motor controller 720 outputs an inverter control commandsignal, a motor field control command signal, and a generator fieldcontrol command signal to the inverter unit 400, the chopper circuit740, and a voltage regulator 240 of the driving-dedicated electric powergenerator 200, respectively, as output information. The inverter controlcommand signal controls driving of the inverter unit 400, the motorfield control command signal controls the field current of the motor100, and the generator field control command signal controls the fieldcurrent of the driving-dedicated electric power generator 200.

The chopper circuits 730, 740 are each a current controller which, onthe basis of the command signals output from the four-wheel drivingcontroller 710 and the motor controller 720, the controller repeatsconducting and cutting off the current supplied from the vehicle-mountedbattery 10, controls an average value of output voltages supplied to anassociated load (excitation winding or field winding), and controls aflow of current into the associated load. Each chopper circuit includeselements such as a switching semiconductor device 731 or 741, a drivercircuit for driving the switching semiconductor device. An excitingcurrent that flows from the vehicle-mounted battery 10 into theexcitation winding (not shown) of the clutch 500 is controlled by thechopper circuit 730. A field current that flows from the vehicle-mountedbattery 10 into the excitation winding 123 (not shown) of the rotor 120of the motor 100 is controlled by the chopper circuit 740.

The driving-dedicated power generator 200 is an AC synchronous rotaryelectric machine which, as described above, is driven by the drivingforce of the engine 6 via a belt and supplies to the inverter unit 400the electric power requested for driving the motor 100. The powergenerator 200 includes a stator 210, a rotor 220, a rectifier 230, andthe voltage regulator 240.

The stator 210 and the rotor 220 are arranged so that central axes ofboth are concentric, and both elements are radially opposed to eachother.

The stator 210 is an armature constructed with armature windings 211wound around an armature core (not shown).

The rotor 220 is a field system of a Rundell-type structure, constructedby winding a magnetic field coil 221 around a magnetic pole core (notshown) on which claw poles magnetized to have one polarity and clawpoles magnetized to have another polarity are circumferentially arrangedat alternate positions, and providing rectangularly parallelepipedicpermanent magnets (not shown) between the circumferentially adjacentclaw poles. Each permanent magnet is magnetized so that polarity of acircumferential face is the same as that of the circumferentiallyopposed claw poles.

The rectifier 230 is a converter that rectifies three-phase AC poweroutput from the armature windings 211, into DC power form. The rectifier230 includes a three-phase bridge rectifying circuit in which threeseries circuits each with two diodes 231 electrically connected inseries for a specific phase are electrically connected in parallel(i.e., connected in bridge form).

In accordance with a command signal output from the motor controller720, the voltage regulator 240 controls a field current supplied to thefield coil 221, and thus controls a supply voltage output from thedriving-dedicated power generator 200. The voltage regulator 240includes elements such as a switching semiconductor device 241 and adriver circuit for driving the switching semiconductor device. Beforethe driving-dedicated power generator 200 starts operating (i.e., whenthe electric power level is too low for a predetermined field current tobe obtained), the field current that flows into the field coil 221 issupplied from the vehicle-mounted battery 10, and after the operationalstart of the driving-dedicated power generator 200, the field current issupplied from an output end of the rectifier 230.

When the field current controlled by the voltage regulator 240 flowsinto the field coil 221 via a conductor (not shown) that achieveselectrical connection by mechanical sliding contact between a brush anda slip ring, the claw poles become magnetized to assume associatedpolarities and hence to form a magnetic circuit in which a set ofmagnetic fluxes that has occurred in the rotor 220 extends from the clawpoles of one polarity through the stator 210 to the claw poles of theother polarity. When the driving force of the engine 6 rotates the rotor220 under that state, the fluxes that have been output from the rotor220 become crossed with the three-phase armature windings 211 and avoltage gets induced in each of the three-phase armature windings 211.Thus, three-phase AC power is output from the armature windings 211. Theoutput three-phase AC power is next rectified into DC power by therectifier 230 and supplied to the inverter unit 400.

The inverter unit 400 is a power converter by which, in accordance witha command signal output from the motor controller 720, the DC poweroutput from the driving-dedicated power generator 200 is converted intothe three-phase AC power required for the driving of the motor 100 andthen the converted three-phase AC power is supplied thereto. Theinverter unit 400 includes a power module 410, a driver circuit 420, asmoothing circuit, and a sensor 440.

The power module 410 is a semiconductor circuit unit constructed so thatthe DC power supplied from the driving-dedicated power generator 200will be converted into three-phase AC power by a switching action of aswitching semiconductor device 411. The power module 410 includes apower conversion circuit in which three series circuits each with twoswitching semiconductor devices 411 electrically connected in series fora specific phase are electrically connected in parallel (i.e., connectedin bridge form). The power module 410 is electrically connected betweenthe driving-dedicated power generator 200 and the motor 100.

The present embodiment uses a metal-oxide-semiconductor field-effecttransistor (MOSFET) as the switching semiconductor device 411. Aparasitic diode is electrically connected between a drain electrode andsource electrode of the MOSFET so that a current flows in a forwarddirection from the source electrode, towards the drain electrode. TheMOSFET has a gate electrode in addition to the drain electrode and thesource electrode.

While an example in which a MOSFET is used as the switchingsemiconductor device 411 is described in the present embodiment, aninsulated-gate bipolar transistor (IGBT) may be used as an alternativefor the MOSFET. If the IGBT is used, the transistor has an emitterelectrode, a collector electrode, and a gate electrode, and a diodeneeds to be provided between the emitter electrode and the collectorelectrode separately.

After receiving command signals output from the motor controller 720,that is, inverter control command signals associated with six switchingsemiconductor devices 411, the driver circuit 420 creates a drivingsignal of a capacity and electric potential required for operation ofeach switching semiconductor device 411. Next, the driver circuit 420supplies the created driving signal to the gate electrode of theswitching semiconductor device 411, thus turning on or off the switchingsemiconductor device 411. The driver circuit 420 is an integratedcircuit (IC) formed by integrating circuit elements such as a pluralityof semiconductor devices constituting an amplifier, a voltage converter,and/or the like.

The smoothing circuit 430 smoothens the DC power supplied to the powermodule 410, by removing ripple components from the DC power suppliedfrom the driving-dedicated power generator 200. The smoothing circuit430 includes a capacitor 431 that is a capacitive element, and iselectrically connected between a DC side of the power module 410 and anoutput side of the driving-dedicated power generator 200.

The sensor 440 includes a voltage sensor for detecting a capacitorvoltage, that is, a DC voltage applied from the output side of thedriving-dedicated power generator 200 to the DC side of the power module410, and a current sensor for detecting a motor armature currentsupplied from an AC side (output side) of the power module 410 to themotor 100. The sensor 440 also includes a temperature sensor fordetecting a temperature of the power module 410.

Although the voltage sensor and the current sensor are collectivelyshown in FIG. 2, both sensors are provided at respective appropriatemeasuring locations in an actual product. The current sensor, forinstance, is provided on an output terminal of the power module 410 oron an electrical interconnecting conductor electrically connected to theoutput terminal.

The motor 100 is a field-winding-type synchronous motor that generatesrotational motive power when driven by the three-phase AC power outputfrom the inverter unit 400. The motor 100 includes a stator 110, a rotor120, and a sensor 140.

The stator 110 and the rotor 120 are arranged so that central axes ofboth are concentric, and both elements are opposed to each other in aradial direction. The stator 110 is an armature constructed with statorcoils (armature windings) 112 wound around a stator core (armature core)not shown. The rotor 120 is a field system constructed by winding afield coil 123 around a magnetic pole core (not shown).

The sensor 140 is a current sensor for detecting a motor field currentsupplied from the chopper circuit 740 to the field coil 123. The sensor140 is also a rotation sensor adapted to detect rotation of the rotor120. Either a resolver that changes according to a particular change ingap present between the rotor 120 and the stator 110, and outputs twovoltages having a phase difference, or a Hall sensor with a Hall element(magnetic response element) that outputs an appropriate signal inresponse to a change in magnetism of a rotating magnetic member is usedas the rotation sensor.

Although the current sensor and the rotation sensor are collectivelyshown in FIG. 2, both sensors are provided at respective appropriatemeasuring locations in an actual product. A rotatable section of therotation sensor, for instance, is provided on a rotating shaft of therotor 120, and a fixed section of the sensor is provided at a regionopposed to the rotatable section of the sensor, in a radial direction.Thus, the rotation sensor outputs a signal in synchronization with therotation of the rotor 120.

When the field current that the chopper circuit 740 has controlled issupplied to the field coil 123 via a conductor (not shown) that achieveselectrical connection by mechanical sliding contact between the brushand the slip ring, the magnetic pole core is magnetized and magneticfluxes occur in the rotor 220. The fluxes that have occurred in therotor 120 pass through the magnetic circuit that returns from the polecore through the stator 110 back to the pole core. In the meantime, whenthe three-phase AC power that has been output from the inverter unit 400is supplied to the stator coil 112, the stator 110 generates a rotatingmagnetic field. The rotating field that the stator 110 has generated,and the magnetic fluxes that the rotor 120 has generated cause magneticattraction and repulsion to occur between the stator 110 and the rotor120. Thus, the rotor 120 rotates and the rotational motive powerresulting from the rotation is output to the rear wheels 4.

The motor 100 will be described in detail later herein using FIG. 3.

As described previously herein, the follower driving system in thepresent embodiment does not have a motor-driving battery. In the presentembodiment, therefore, almost no DC power can be absorbed between thedriving-dedicated power generator 200 and the inverter unit 400. Inaddition, the present embodiment employs current rotation based on d-qaxis rotational coordinates, that is, so-called spectral control thatallows highly responsive and highly accurate torque control of theinverter unit 400, and slow-response field current control of thedriving-dedicated power generator 200. Accordingly, driving control ofthe motor 100 and power-generating control of the driving-dedicatedpower generator 200 are coordinated in the present embodiment so thatthe power-generating energy output from the driving-dedicated powergenerator 200, and consumption of the driving energy input to theinverter unit 400 and the motor 100 will be equal to each other. Thismakes the present embodiment able to prevent overvoltage due to surpluselectric power from occurring in the capacitor 431 and the switchingsemiconductor device 411, and to avoid a lack of torque in the motor 100due to a voltage decrease of the capacitor 431, caused by insufficiencyin electric power.

Additionally, since as described previously herein, the presentembodiment cannot absorb practically any DC power between thedriving-dedicated power generator 200 and the inverter unit 400,regenerative operation of the motor 100 is basically impossible. Forthis reason, during the braking of the four-wheel drive vehicle 1, thepresent embodiment disengages the clutch 500 to interrupt thetransmission of power between the rear wheels 4 and the motor 100, andhence to prevent the motor 100 from being driven by the driving force ofthe rear wheels 4. This makes it possible to prevent regenerativeoperation of the motor 100 in the present embodiment.

Furthermore, the present embodiment employs rectangular-wave control andpulse width modulation (PWM) control as switching control schemes forthe inverter unit 400. Rectangular-wave control or PWM control isselectively used, depending upon an operating point (speed) of the motor100. For example, PWM control is used for a stop or start of the vehicleand for low-speed traveling thereof (e.g., at a motor speed less than5,000 rpm), and rectangular-wave control is used for middle-speed orhigh-speed traveling of the vehicle (e.g., at a motor speed of 5,000 rpmor more). In the present embodiment, therefore, during rectangular-wavecontrol, one pulse waveform is output for a half period of a fundamentalsine wave, and during PWM control, a plurality of pulse waveformsmodulated in pulse width are output for the half period of thefundamental sine wave.

Next, a configuration of the motor 100 will be described using FIGS. 3to 7.

The present embodiment uses a field-winding-type synchronous motor,especially that having a Rundell-type rotor, as the rear-wheel drivingmotor 100 mounted in the four-wheel drive vehicle 1. The reasons forthis are that the motor 100 is required to have the performancecharacteristic that the operating point is wide, and that an inductionmotor or permanent-magnet-type synchronous motor field-proven forvehicle driving does not always satisfy that requirement.

For example, to start the four-wheel drive vehicle 1 from a heavilysnow-covered place, it becomes essential that the start be executableonly by driving the rear wheels. A large torque is therefore required ina low-speed region of four-wheel drive vehicle 1. In addition, since therear-wheel driving motor mounted in the four-wheel drive vehicle 1 isinstalled near the differential gear at the bottom of the vehicle body,physical dimensions thereof are limited and as mentioned above, a largetorque is required, so a large gear ratio is assigned. To continuefour-wheel driving in up to the middle-speed traveling region of thefour-wheel drive vehicle 1, therefore, the motor for driving the rearwheels needs to be rotated at a very high speed.

However, the induction motor is neither suitable for low-voltagedriving, nor sufficient in low-speed high-torque startingcharacteristics of the vehicle.

In addition, the permanent-magnet-type synchronous motor requiresfield-weakening control that weakens the field system by counteractingthe magnetic fluxes of the permanent magnet in order to suppress voltageinduction at a high-speed rotating side, and a rotating speed has itslimits. If the rotating speed range is too wide, therefore, thepermanent-magnet-type synchronous motor does not always permit drivingin up to a necessary high-speed region, since motor efficiency at thehighs-speed rotating side decreases and since temperature increasessignificantly.

In contrast to the above two kinds of synchronous motors, thefield-winding-type synchronous motor, especially, that having aRundell-type rotor can output a large torque at a low-speed rotatingside, reduce field fluxes by suppressing a field current to suppress avoltage induced, and conduct driving in up to a necessary high-speedregion.

That is to say, the field-winding-type synchronous motor with aRundell-type rotor has a plurality of claw poles created by bending apole core, the claw poles of different polarities are arranged atalternate positions in a circumferential direction, and a field coil iswound cylindrically around a cylindrical section at an inner-surfaceside of the claw poles. Because of this, the field-winding-typesynchronous motor with a Rundell-type rotor can be basically mademultipolar and since the field coil is strong against centrifugal force,the synchronous motor is suitable for high-speed rotation. In addition,a maximum achievable speed range can be broadened and field-weakeningcontrol can be simplified by controlling arbitrarily the field current.

There is a field-winding-type synchronous motor with a salient-pole-typerotor, but this synchronous motor is not suitable for high-speedrotation.

In addition, the field-winding-type synchronous motor with aRundell-type rotor can easily strengthen the field system by having apermanent magnet between claw poles different in polarity. That is tosay, the field-winding-type synchronous motor with a Rundell-type rotorhas a magnetic circuit in which the magnetic fluxes pass through a rotorinterior, and a magnetic circuit in which the magnetic fluxes enter astator from the rotor via an air gap formed between the rotor and thestator and then return from the stator via the air gap to the rotor.During the vehicle start, since the large field current supplied to thefield coil saturates the former magnetic circuit, a large portion of thefluxes of the permanent magnet provided between the claw poles passthrough the latter magnetic circuit. A consequential increase in thequantity of fluxes entering the stator increases the torque. Duringhigh-speed rotation, however, since field-weakening control reduces thecurrent supplied to the field coil and hence lessens the saturation ofthe former magnetic circuit, the fluxes of the permanent magnet thatpass through the latter magnetic circuit are reduced.

In this way, the field-winding-type synchronous motor with aRundell-type rotor automatically operates so that an increase in thefield current increases the quantity of fluxes passing through thelatter magnetic circuit, and so that a decrease in the field currentreduces the quantity of fluxes passing through the latter magneticcircuit. Such operation of the synchronous motor improves the motortorque at the low-speed side and raises motor efficiency at thehigh-speed side.

In the present embodiment, therefore, the field-winding-type synchronousmotor with a Rundell-type rotor is applied as the motor 100 for drivingthe rear wheels of the four-wheel drive vehicle 1, and the quantity ofmagnetic fluxes occurring is actively made variable by changing thefield current with respect to the motor speed (the operating point ofthe motor 100). Thus, the operating point of the motor 100 can be drivenwithin a permissible current range thereof at a maximum voltage of themotor-driven system of the four-wheel drive vehicle 1.

In addition, as described previously, the motor 100 for driving the rearwheels of the four-wheel drive vehicle 1 is installed at an underfloorposition of the vehicle body, near the differential gear 600. To ensurewater-proofing of the motor 100, therefore, the motor needs to be of anenclosed structure, and only natural cooling with externally releasedheat is adoptable since water-cooled or other forms of forced coolingcannot be adopted for reasons associated with dimensional limitation. Ascan be seen from these facts, the motor 100 is subjected tocooling-associated restrictions according to the particular installationenvironment. Because of this, it is necessary that the amount of heatoccurring in the motor 100 should be suppressed for minimum internaltemperature rise thereof.

As described previously, the motor 100 is of the enclosed water-prooftype with a first housing 101, a second housing 102, a third housing103, and a rear cover 104 arranged next to one another in an axialdirection in that order, and adjacent ones of these elements are securedvia bolts, screws, and/or other fasteners, thereby to form a casing.

The first housing 101 is constituted by integrated formation of a firstframe 101 a and a first bracket 101 b. The second housing 102 isconstituted by integrated formation of a second frame 102 a and a secondbracket 102 b. The third housing 103 is constituted by integratedformation of a third frame 103 a and a third bracket 103 b.

The first to third frames 101 a, 102 a, 103 a are each a cylindricalmember having a circular and hollow inner surface. The first bracket 101b is an annular plate member blocking an opening at one lateral end ofthe first frame 101 a in an axial direction thereof and having anaxially penetrating circular hole in a central section of the member.The second bracket 102 b is an annular plate member blocking an openingat the other lateral end of the first frame 101 a in the axial directionthereof and an opening at one lateral end of the second frame 102 a inan axial direction thereof, and having an axially penetrating circularhole in a central section of the member. The third bracket 103 b is anannular plate member blocking an opening at the other lateral end of thesecond frame 102 a in the axial direction thereof and an opening at onelateral end of the third frame 103 a in an axial direction thereof, andhaving an axially penetrating circular hole in a central section of themember. An opening at the other lateral end of the third frame 103 a inthe axial direction thereof is blocked by the rear cover 104. The rearcover 104 is a plate-shaped member formed along an outer surface of thethird frame 103 a.

A motor room 105 is formed in a section surrounded by the first frame101 a, the first bracket 101 b, and the second bracket 102 b. Anelectricity supply room 106 is formed in a section surrounded by thesecond frame 102 a, the second bracket 102 b, and the third bracket 103b. A sensor room 107 is formed in a section surrounded by the thirdframe 103 a, the third bracket 103 b, and the rear cover 104. The motorroom 105, the electricity supply room 106, and the sensor room 107 arearranged next to one another in an axial direction in that order fromone lateral end (output shaft) of each room in the axial direction,along a shaft 126. Adjacent casing members are each connected togetherin a sandwiched condition via a sealing member, whereby airtightness atthe connections between the adjacent casing members is enhanced to raisehermetical sealability of each room.

Although an example in which casing interior is divided into three roomsis described in the present embodiment, the number of rooms may be twoor one. That is to say, the electricity supply room 106 and the sensorroom 107 may be integrated into one room, or the motor room 105, theelectricity supply room 106, and the sensor room 107 may be integratedinto one room. Such integration is effective for integrating theinverter unit 400 axially with respect to the motor 100.

The first bracket 101 b has a first bearing 108 at a central section.The second bracket 102 b has a second bearing 109 at a central section.The first bearing 108 and the second bearing 109 rotatably support theshaft 126. The shaft 126 extends outward in an axial direction thereof,compared with the first bracket 101 b and the second bracket 102 b.

The motor room 105 internally has a stator 110 at the inner surface sideof the first frame 101 a. At an inner surface side of the stator 110, arotor 120 is opposedly disposed via an air gap.

The stator 110 is a stationary section that generates a rotating fieldand has a stator core 111 for constructing a magnetic circuit, and astator coil 112 mounted on the stator core 111 in order to create therotating field.

The stator core 111 is a cylindrical magnetic material formed bystacking a plurality of silicon steel plates in an axial direction, thenproviding laser welds in several places on an outer surface of acylindrical body consequentially obtained, and integrating the pluralityof silicon steel plates. The outer surface is engaged with an innersurface of the first frame 101 a by shrinkage fitting or the like,thereby to be secured to the first frame 101 a. The outer surface of thestator core 111 forms a cylindrical yoke (not shown) that has acylindrical wall thicker than an enclosure member. A plurality of teeth111 a are formed integrally with the yoke at the inner surface sidethereof. The plurality of teeth 111 a are formed continuously in anaxial direction, extend from an inner surface of the yoke, towards aninner section in a radial direction, and are arranged at equal spatialintervals in a circumferential direction. A plurality of slots 111 b areformed in an inner surface portion of the stator core 111 and betweencircumferentially adjoining teeth 111 a. The plurality of slots 111 bform a slender coil storage section recessed from the inner surface ofthe stator core 111, towards an outer section thereof in the radialdirection, in such a form as to be opened at the inner surface side ofthe core 111, and extending from one lateral end thereof in the axialdirection, through the inner surface thereof, towards the other lateralend of the core 111 in the axial direction. As with the plurality ofteeth 111 a, the slots 111 b are arranged at equal spatial intervals ina circumferential direction.

The stator coil 112 is constituted by three star-connected phase coils(u-phase, v-phase, and w-phase). Star connection is an electricalconnection scheme in which each phase coil is interconnected at one endso that the neutral point is formed. The stator coil 112 may use deltaconnection instead. Delta connection is an electrical connection schemein which one of two ends of a first phase coil is connected to one endof a second phase coil and one end of a third phase coil is connected tothe other end of the second phase coil.

Each phase coil is constructed by electrical connection of multiple coilconductors 113 (unit coils) for each phase, stored within each slot 111b. The coil conductors 113 are each a segment conductor stored acrossseveral slots 111 b, in two slots 111 b spaced according to a particularpole pitch of the rotor 120, the conductor being formed by onecontinuous copper wire having an enamel-insulated outer surface (i.e., acopper wire formed into a no-end state from one edge of the conductor toanother edge). Two coil conductors 113 are stored in a verticaldirection (depthwise or in a radial direction of the stator core 111) ineach slot 111 b. In other words, the present embodiment employsdouble-layer coiling to constitute the stator coil 112.

An example in which a segment conductor formed from a rectangular wirethat has a rectangular sectional shape in an extending direction of theconductor (i.e., in an axial or longitudinal direction of the conductor)or has a rectangular cross-sectional shape is used as the coil conductor113 is taken in the description of the present embodiment. The coilconductor 113 may have an elliptical sectional shape in the extendingdirection of the conductor (i.e., in the axial or longitudinal directionof the conductor), an elliptical cross-sectional shape, or any othershape resembling a rectangular shape, such as a shape created bysandwiching a round wire from two directions, thus forming a non-roundwire, and then further forming a planar cross-sectional portion. Thepresent embodiment uses a rectangular wire as the coil conductor 113,thereby to increase a rate of a cross-sectional area (i.e., spacefactor) of the coil conductor 113 in the extending direction thereof,with respect to an axial cross-sectional area of the slot 111 b.

Hereinafter, the section of the coil conductor 113 in the presentembodiment in the direction that the conductor extends (i.e., in theaxial or longitudinal direction of the conductor) or the cross sectionof the conductor is referred to simply as the section.

Other constituent elements of the coil conductor 113, a method ofconnecting coil conductors 113, and other aspects will be described indetail using FIGS. 4 to 7.

The rotor 120 rotates by magnetic actions of the stator 110. In thepresent embodiment, the rotor 120 is of tandem construction. The tandemconstruction here refers to construction with a plurality of magneticpole cores arranged next to one another in an axial direction on oneoutput shaft 126. In the present embodiment, a first magnetic pole coreand a second magnetic pole core are axially arranged next to each otherto constitute the tandem type of rotor 120.

The first magnetic pole core (second magnetic pole core) includes afirst claw pole core 121 a, 122 a (second claw pole core 121 b, 122 b),a first field coil 123 a (second field coil 123 b), and a firstpermanent magnet 125 a (second permanent magnet 125 b). The first andsecond magnetic pole cores are engaged with an outer surface of theshaft 126 so that claw pole cores of the same polarity are arrangedadjacently to each other, for example, so that the first claw pole core122 a that functions as an N-pole in the first magnetic pole core, andthe second claw pole core 121 b that functions as an N-pole in thesecond magnetic pole core are arranged adjacently to each other.

The first claw pole core 121 a, 122 a (second claw pole core 121 b, 122b) is axially opposed and has a plurality of claws each extending from acylindrical portion of the pole core, towards a radial outer portionthereof, bent in the opposing direction of the pole core, and furtherextending in the opposing direction thereof. Both the first and secondmagnetic pole cores include 12 claws (6 claws at the N-pole side and 6claws at the S-pole side). Briefly, the rotor 120 in the presentembodiment has 12 magnetic pole pieces. Each claw has a trapezoidal ortriangular outer surface so that circumferential width of the clawprogressively decreases as it goes from a proximal end of the clawtowards a distal end thereof, and a right-angled triangularcircumferential (lateral) surface so that radial thickness of the claw(i.e., a relative radial distance of the inner surface side of the clawwith respect to the outer surface side thereof) decreases progressivelyas it goes from the proximal end of the claw towards the distal endthereof. As a result of the axially opposed disposition of the firstclaw pole core 121 a, 122 a (second claw pole core 121 b, 122 b), therespective claws are arranged at alternate positions in thecircumferential direction. That is to say, claws different in polarityare arranged circumferentially at alternate positions.

A first bobbin 124 a (second bobbin 124 b) is mounted in a region formedbetween an outer surface side of two axially juxtaposed cylindricalportions of the first claw pole core 121 a, 122 a (second claw pole core121 b, 122 b), and an inner surface side of the multiple claws arrangedin the circumferential direction of the first claw pole core 121 a, 122a (second claw pole core 121 b, 122 b). The first bobbin 124 a and thesecond bobbin 124 b are both formed from a member having an electricalinsulating property, for example, from an insulating-resin formedelement. A first field coil 123 a (second field coil 123 b) constructedby winding a round wire through a plurality of turns in acircumferential direction is wound around the first bobbin 124 a (secondbobbin 124 b).

When the first field coil 123 a (second field coil 123 b) is excited bya field current, the claws of the first claw pole core 121 a (secondclaw pole core 122 b) are magnetized to function as the S-pole, and theclaws of the first claw pole core 122 a (second claw pole core 121 b),as the N-pole.

A first permanent magnet 125 a (second permanent magnet 125 b) is heldin sandwiched form between every two circumferentially adjacent claws ofthe first claw pole core 121 a, 122 a (second claw pole core 121 b, 122b). The first permanent magnet 125 a and the second permanent magnet 125b are magnetized so as to generate magnetic fluxes in a direction(circumferential direction) opposed to the circumferential (lateral)face of each claw of the claw pole core, and so that the polarity of aface opposed to the circumferential (lateral) face of each claw of theclaw pole core is the same as the polarity of the claws of thecircumferentially opposed claw pole cores.

While magnetic pole centers of the first and second magnetic pole coresin the present embodiment are aligned, the magnetic pole centers may beshifted from each other according to the number of magnetic pole coresjuxtaposed (in tandem form) or the number of coil conductors 113 arrayedcrosswise along the slots 111 b of the stator core 111. For example,since the number of magnetic pole cores juxtaposed in the presentembodiment is two, the magnetic pole centers of the first and secondmagnetic pole cores may be shifted through 30 degrees in electricalangle (5 degrees in mechanical angle). Shifting the magnetic polecenters of the first and second magnetic pole cores in this fashionmakes it possible to reduce a torque ripple and hence to reducevibration and noise.

The first field coil 123 a and the second field coil 123 b areelectrically connected to one pair of slip rings 130 arranged in theelectricity supply room 106. The slip rings 130 are electroconductiveannular members, which are provided on an outer surface of a shaftextension 126 a extending towards the electricity supply room 106. Onepair of brushes 131 are in sliding contact on an outer surface of theslip ring pair 130. One of the brushes 131 is electrically connected toa voltage regulator, and is supplied with a field current controlled bythe voltage regulator. The field current that has been supplied to oneof the brushes 131 is further supplied to the first field coil 123 a andthe second field coil 123 b via the slip ring pair 130 and excites thecoils 123 a, 123 b. Thus, the claws of the first claw pole core 121 aand second claw pole core 122 b are magnetized to function as theS-pole, and the claws of the first claw pole core 122 a and second clawpole core 121 b, as the N-pole.

The paired brushes 131 are each held by a brush holder 132, and eachbrush 131 is urged onto the outer surface of the associated slip ring130 by a resilient pressure so as to come into sliding contact with theassociated slip ring 130.

A resolver 140 for detecting the magnetic pole position of the rotor 120is stored within the sensor room 107. The resolver 140 includes aresolver stator 141 and a resolver rotor 142 disposed opposedly to theresolver stator 141 via a mechanical air gap at the inner surface sideof the resolver stator 141. The resolver 140 uses the resolver stator141 to sense a magnetic change due to rotation of the resolver rotor142, and outputs a signal associated with the sensed change, from theresolver stator 141 to the motor controller 720.

The resolver stator 141 is fixed to an inner surface of the third frame103 a. The resolver rotor 142 is fitted on an outer surface of a shaftextension 126 b and opposed to the inner surface side of the resolverstator 141. The shaft extension 126 b is a region extending more outwardin an axial direction than the shaft extension 126 a, and forms an endopposite to an output end 126 c of the shaft 126 mechanically connectedto the differential gear 600 via the clutch 500. Thus, the resolverrotor 142 rotates with the rotor 120.

A reference position of the resolver 140 may be set so as to match tomagnetic centers of the first and second claw pole cores or may be setso as to match to a resultant induced voltage waveform obtained bycombining a waveform of an induced voltage generated by the first clawpole core, and a waveform of an induced voltage generated by the secondclaw pole core. A position of the resolver stator 141 can be easilyadjusted by removing the rear cover 104.

An example in which the resolver 140 is used as a magnetic pole positiondetector is described in the present embodiment. The magnetic poleposition detector may be constructed of a permanent magnet and magneticresponse elements such as Hall elements for sensing magnetic fluxes ofthe permanent magnet. In this case, the permanent magnet is rotated withthe rotor of the motor, and Hall elements for three phases are arrangedat an electrical angle interval of 120 degrees around the permanentmagnet.

Next, a configuration of the stator coil 112 is described in detailusing FIGS. 4 to 7.

As described previously, the stator coil 112 is constructed by mountinga plurality of coil conductors 113 in a plurality of slots 111 bprovided in the stator core 111, and electrically connecting theplurality of coil conductors 113.

Each coil conductor 113 is a segment conductor formed by sequentiallyconducting three forming steps (in FIGS. 5A to 5D) upon one continuousrectilinear rectangular wire 116 (in FIG. 5A) and finally, forming thewire 116 into a divergent form as shown in FIG. 5D. The forming stepsare split into slot pre-insertion forming shown in FIGS. 5A to 5C, andslot post-insertion forming shown in FIG. 5D.

First in the slot pre-insertion forming step, as shown in of FIG. 5A,enamel insulation is mechanically stripped from proximal ends 116 e and116 f of one rectilinear rectangular conductor 116 obtained by cutting arectangular-shaped wire to required length (the proximal ends 116 e, 116f are associated with respective connecting portions of both proximalends of the coil conductor 113).

After that, the rectangular conductor 116 is bent so that with a bendingaxis set on a line segment 116 b which lengthwise bisects two faces of asmaller area among all four faces parallel to a central axis of theconductor 116, a rectilinear portion 116 c at one side of the segment116 b and a rectilinear portion 116 d at the other side of the segment116 b are arranged next to each other in parallel and extend in the samedirection. That is to say, the rectangular conductor 116 is placed on aplane with one of two faces of a larger area of the conductor 116 as aplacement surface, and the conductor 116 is bent into two parts midwayin the lengthwise direction, along the placement surface of theconductor 116. The segment 116 b is shifted to one side in thelengthwise direction of the rectangular conductor 116, rather thancentrally in the lengthwise direction.

Lateral width (maximum width) of the rectangular conductor 116, in anaxial rectangular section thereof, is greater than width of an openingin a slot 111 b (i.e., maximum circumferential width of the stator core111).

As shown in FIG. 5B, a U-shaped first formed conductor 117 is formed byexecution of the above forming step. The first formed conductor 117includes side portions 117 a and 117 b, and a bent-over portion 117 c.

The side portions 117 a, 117 b are rectilinear portions arranged next toeach other in parallel on one plane and extending in the same direction,and each side portion has proximal ends 117 h and 117 i formed bystripping the enamel insulation, as end portions formed at a sideopposite to the bent-over portion 117 c. In the present embodiment, theside portion 117 b is formed to be longer than the side portion 117 a sothat axial layout positions of the two proximal ends of the coilconductor 113 are equal at an axial end of the stator core 111. Thus,changes in the lengths of the side portions due to subsequent formingare accommodated.

The bent-over portion 117 c is a U-shaped portion that links one end ofthe side portion 117 a, 117 b (i.e., the end opposite to the proximalend 117 h, 117 i). The bent-over portion 117 c extends from one lateralend of the side portion 117 a, 117 b, is bent over midway for a turnthrough 180 degrees, and leads to the other lateral end of the sideportion 117 a, 117 b.

Next as shown in FIG. 5B, the side portion 117 a of the first formedconductor 117 is bent with bending axes set on two line segments 117 dand 117 e which lengthwise bisect two faces of a smaller area among allfour faces parallel to a central axis of the side portion 117 a, at alateral end of the bent-over portion 117 c, and then the side portion117 a is spread away from the side portion 117 b so that a clearance ofthe same dimension as a pitch of two slots spaced according to aparticular rotating pole pitch is formed between the side portions 117 aand 117 b, and so that a stepped portion based on a radial (depthwise)dimension of the slots 111 b (i.e., based on layout of upper and lowerlayers of the coil conductor 113 inside the slots 111 b) is formedbetween the side portions 117 a and 117 b. That is to say, the sideportion 117 b is fixed and only the side portion 117 a is pulled so thatthe side portion 117 a moves towards a rear side of the paper of thedrawing.

As shown in FIG. 5C, a U-shaped second formed conductor 118 is formed byexecution of the above forming step. The second formed conductor 118includes side portions 118 a and 118 b, and a crossover 118 c.

The side portions 118 a, 118 b are rectilinear portions provided next toeach other in parallel with a stepped portion thereon that is based onthe radial (.depthwise) dimension of the slots 111 b, and extending inthe same direction. Each side portion 118 a, 118 b has proximal ends 118g and 118 h formed by stripping the enamel insulation, as end portionsformed at a side opposite to the crossover 118 c.

The crossover 118 c is a right-angled triangular portion provided at onelateral end of the side portion 118 a, 118 b (i.e., an end opposite tothe proximal end 118 g, 118 h). In order that a clearance equivalent tothe pitch of two slots spaced according to the particular rotating polepitch is formed between the side portions 118 a and 118 b, the crossover118 c crosses over from one of the two side portions 118 a, 118 b to theother thereof and links the side portions 118 a, 118 b at one lateralend. The crossover 118 c includes crossover side portions 118 d and 118e, and a bent-over portion 118 f.

The crossover side portion 118 d is a rectilinear portion extendingrectilinearly from one lateral end of the side portion 118 a (i.e., anend opposite to the proximal end 118 g), in a direction of the endopposite to the proximal end 118 g. The crossover side portion 118 e isan inclined portion extending from one lateral end of the side portion118 h (i.e., an end opposite to the proximal end 118 h), in a directionof the end opposite to the proximal end 118 g, while at the same timeextending in a crossover direction. The bent-over portion 118 f is aU-shaped portion that links the opposite lateral ends of the crossoverside portions 118 d, 118 e with respect to the side portions 118 a, 118b so as to make the extending directions of the crossover side portions118 d, 118 e change from one of the crossover side portions 118 d, 118 eto the other crossover side portion. The bent-over portion 118 f extendstowards a stepped portion formed between the crossover side portions 118a, 118 b.

Next before the slot post-insertion forming step, a slot insertion stepis executed and the second formed conductor 118 is mounted in two spacedslots 111 b. The proximal ends 118 g and 118 h of the second formedconductor 118 are inserted from a rear end opposite to one axial end ofthe stator core 111 (with respect to a front output end of the shaft126), into the two spaced slots 111 b in such a form as to get overseveral slots 111 b. At this time, one of the side portions 118 a and118 b (in the present embodiment, the side portions 118 b) is insertedinto an upper layer of the slots 111 b (i.e., depthwise bottom end ofthe slots), and the other of the side portions 118 a and 118 b (in thepresent embodiment, the side portions 118 a) is inserted into a lowerlayer of the slots 111 b (i.e., depthwise open end of the slots). Thesecond formed conductor 118 is inserted so that the longitudinaldirection of the section of the conductor equals the depthwise directionof the slots 111 b.

The second formed conductor 118 is inserted into the two spaced slots inorder by the execution of the above insertion step. When the insertionstep is completed, multiple crossovers 118 c are arranged at one axiallateral end of the stator core 111 (i.e., the insertion end of thesecond formed conductor 118) and a formed annular array structure isformed. In addition, at the other axial lateral end of the stator core111 (i.e., the end opposite to the insertion end of the second formedconductor 118), the open ends of multiple side portions 118 a, 118 bthat include the proximal ends 118 g, 118 h are arranged so as toprotrude axially from the slots 111 b, and another formed annular arraystructure is formed.

In the present embodiment, since the number of rotating pole pieces is12 and that of slots is 36, the rotating pole pitch is equivalent to 3slots of space. Accordingly, when the side portion 118 b of the secondformed conductor 118 is inserted into the upper layer of one of the twospaced slots 111 b, the side portion 118 a of the second formedconductor 118 is inserted into a lower layer of the third slot 111 bfrom one of the two spaced slots 111 b.

Quantitative combinations of rotating pole pieces and slots include, forexample, a combination of 12 pole pieces and 72 slots, in which case,the rotating pole pitch is equivalent to 6 slots of space.

Next, as shown in FIG. 5D, the slot post-insertion step is executed. Inthe slot post-insertion step, the open ends of the side portions 118 a,118 b of the second formed conductor 118 which has been inserted intothe two spaced slots 111 b are spread away from each other so that abending direction of the open ends becomes inverse with respect to thecrossover direction of the crossover 118 c and so that an extendingdirection of the associated proximal ends (118 g, 118 h) equals theinsertion (axial) direction of the second formed conductor 118 withrespect to the stator core 111. After being spread, the open ends areboth bent using two bending axes. The bending axes here are, as shown inFIG. 5B, two line segments 117 f, 117 g which lengthwise bisect twofaces of a smaller area among all four faces parallel to an axis of theside portion 117 a, 117 b of the first formed conductor 117, at theproximal end 117 h, 177 i.

As shown in FIG. 5D and in FIG. 6, a coil conductor 113 is formed byexecution of the above forming step. The coil conductor 113 includesside portions 113 a and 113 b, a crossover-side coil end 113 c, and aconnecting-side coil end 113 d.

The side portion 113 a is a rectilinear portion stored in one of twospaced slots 111 b and disposed in an upper layer thereof (i.e., in adepthwise bottom end of the slots). The side portion 113 b is arectilinear portion stored in the other of the two spaced slots 111 band disposed in a lower layer thereof (i.e., in a depthwise open end ofthe slots).

The crossover-side coil end 113 c is a right-angled triangular portiondisposed at one axial lateral end of the stator core 111 (i.e., at theinsertion end of the second formed conductor 118 with respect to theslots 111 b), provided at one of the side portions 113 a, 113 b (i.e.,at a side opposite to the connecting-side coil end 113 d), guidedoutward from the slots 111 b, crossing over from one of the sideportions 113 a, 113 b to the other thereof through a distance equivalentto a pitch of two slots spaced according to a particular rotating polepitch, and linking the side portions 113 a, 113 b at one lateral end ofeach thereof. The crossover-side coil end 113 c includes crossover sideportions (outward guide portions) 113 e, 113 f, and a bent-over portion113 g.

The connecting-side coil end 113 d is a portion disposed at the otheraxial end of the stator core 111 with respect to the crossover-side coilend 113 c (i.e., disposed at the side opposite to the insertion end ofthe second formed conductor 118 with respect to the slots 111 b),provided at the other of the side portions 113 a, 113 b (i.e., at a sideopposite to the crossover-side coil end 113 c), guided outward from theslots 111 b, extending in an opposite direction with respect to thecrossover direction of the crossover-side coil end 113 c, and connectedto a connecting-side coil end 113 d of any other coil conductor 113extending in a fashion similar to that of the connecting-side coil end113 d of the coil conductor 113 shown in FIG. 5D and in FIG. 6. Theconnecting-side coil end 113 d includes crossover side portions (outwardguide portions) 113 h, 113 i, and connecting portions 113 j, 113 k.

The crossover side portion 113 e is a rectilinear portion extendingrectilinearly from one lateral end of the side portion 113 a (i.e., anend opposite to the connection 113 j), in a direction of the endopposite to the proximal end 118 g. The crossover side portion 113 f isan inclined portion extending from one lateral end of the side portion113 b (i.e., an end opposite to the connection 113 k), in a direction ofthe end opposite to the connection 113 k (i.e., a direction in which thecrossover side portion axially is away from the stator core 111), whileat the same time extending in a crossover direction. The bent-overportion 113 g is a U-shaped portion that links the opposite lateral endsof the crossover side portions 113 e, 113 f with respect to the sideportions 113 a, 113 b so as to make the extending directions of thecrossover side portions 113 e, 113 f change from one thereof to theother thereof. The bent-over portion 113 g extends towards a steppedportion formed between the crossover side portions 113 a, 113 b (i.e.,towards a stepped portion between the upper and lower layers in thedepthwise direction of the slots).

The crossover-side coil end 113 c here is formed so that as shown inFIG. 4, an opening angle θ1 (mechanical angle) of the crossover side ofthe crossover side portion 113 e with respect to one axial lateral edgeof the stator core 111 (i.e., the insertion end of the second formedconductor 118 with respect to the slots 111 b) is larger than an openingangle θ2 (mechanical angle) of the crossover side of the crossover sideportion 113 f with respect to the same edge of the stator core 111. Inthe present embodiment, θ1 is 90 degrees. Also, θ2 is smaller than θ1and decreases below 45 degrees.

In addition, the crossover-side coil end 113 c is formed so that becauseof the relationship between the angles θ1 and θ2 of the crossover sideportions 113 e, 113 f, length of the crossover side portion 113 f fromone lateral end of the side portion 113 b (i.e., an opposite end withrespect to the connection 113 k) to the bent-over portion 113 g is, asshown in FIG. 4, greater than length of the crossover side portion 113 efrom one lateral end of the side portion 113 a (i.e., an opposite endwith respect to the connection 113 j) to the bent-over portion 113 g.

Furthermore, the crossover-side coil end 113 c is formed so that becauseof the relationship between the angles θ1 and θ2 of the crossover sideportions 113 e, 113 f, a layout position of the bent-over portion 113 gin the circumferential direction of the stator core 111 (i.e., thecrossover direction of the crossover-side coil end 113 c) is, as shownin FIG. 6, present on an extension line of the side portion 113 a, withan offset thereto, compared with an intermediate position of the pitchof the two slots spaced according to the particular rotating pole pitch.

The crossover side portion 113 h is an inclined portion extending fromthe other lateral end of the side portion 113 a (i.e., an end oppositeto the bent-over portion 113 g), in a direction opposite to thebent-over portion 113 g (i.e., a direction in which the crossover sideportion axially is away from the stator core 111), while at the sametime extending in a direction opposite to the direction in which thecrossover side portion crosses over from the side portion 113 f, towardsthe side portion 113 e. The connection 113 k is a portion formed at aproximal end opposite to the side portion 113 a of the crossover sideportion 113 h, and connected to the connection 113 k under the state inwhich the connection overlaps the connection 113 k existing at theproximal end of the inclined portion extending from the side portion 113b disposed in an upper layer of any other coil conductor 113 storedwithin other slots 111 b.

The crossover side portion 113 i is an inclined portion extending fromthe other lateral end of the side portion 113 b (i.e., the end oppositeto the bent-over portion 113 g), in the direction opposite to thebent-over portion 113 g (i.e., a direction in which the crossover sideportion axially is away from the stator core 111), while at the sametime extending in the direction opposite to the direction in which thecrossover side portion crosses over from the side portion 113 f, towardsthe side portion 113 e. The connection 113 k is a portion formed at aproximal end opposite to the side portion 113 b of the crossover sideportion 113 i, and connected to the connection 113 j under the state inwhich the connection overlaps the connection 113 j existing at theproximal end of the inclined portion extending from the side portion 113a disposed in a lower layer of any other coil conductor 113 storedwithin other slots 111 b.

The connections 113 j, 113 k overlap each other in the same direction asthat in which the stepped portion formed between the side portions 113a, 113 b is present (i.e., this stepped portion is formed between thedepthwise upper and lower layers of the slots and is also the steppedportion present in the radial direction of the stator core 111).

A plurality of elements to be connected are formed at the other axiallateral end of the stator core 111 (i.e., the lateral end opposite tothe insertion end of the second formed conductor 118) by the executionof the above forming steps. More specifically, each element to beconnected includes the connection 113 j of one of two coil conductors113 (e.g., the proximal end of the crossover side portion 113 hextending from the side portion 113 a of the coil conductor 113 disposedin the lower layer of the fourth right-side slot 111 b from the slot 111b at a left end of FIG. 6), and the connection 113 k of the other of thetwo coil conductors 113 (e.g., the proximal end of the crossover sideportion 113 i extending from the side portion 113 b of the coilconductor 113 disposed in the upper layer of the seventh right-side slot111 b from the slot 111 b at the left end of FIG. 6). At this time, theplurality of elements to be connected are arrayed in a crossoverdirection of the connections 113 j, 113 k (i.e., the circumferentialdirection of the stator core 111) with the positions of the connections113 j, 113 k matching in the crossover direction (i.e., thecircumferential direction of the stator core 111) and with theconnections 113 j, 113 k overlapping each other in the direction of thestepped portion formed between the side portions 113 a, 113 b. Thus, anannular protruding array structure is formed at the other axial lateralend of the stator core 111 (i.e., the lateral end opposite to theinsertion end of the second formed conductor 118) by the plurality ofelements to be connected.

A clearance between crossover side portions 113 e adjacent to each otherin the crossover direction is larger than a clearance between crossoverside portions 113 f adjacent to each other in the crossover direction,as shown in FIG. 6. A clearance between crossover side portions 113 hadjacent to each other in the crossover direction is dimensionally equalto a clearance between crossover side portions 113 i adjacent to eachother in the crossover direction, as shown in FIG. 6. In addition, theclearance between the adjacent crossover side portions 113 h in thecrossover direction, and the clearance between the adjacent crossoverside portions 113 i in the crossover direction are, as shown in FIG. 6,smaller than a maximum clearance between the adjacent crossover sideportions 113 e in the crossover direction, and larger than a minimumclearance between the adjacent crossover side portions 113 f in thecrossover direction.

Although not shown, insulation is provided in sandwiched form in theclearance between the adjacent crossover side portions 113 f in thecrossover direction.

As shown in FIG. 6, layout positions of the elements to be connectedthat include the connections 113 j, 113 k, in the circumferentialdirection of the stator core 111 (i.e., the crossover direction of thecrossover-side coil end 113 c), differ from a layout position of thebent-over portion 113 g and are somewhere in between the two slotsspaced according to the particular rotating pole pitch.

The connections 113 j, 113 k are each connected by resistance brazing.This electrically interconnects in series the coil conductors 113constituting the phase coils for each phase. At a neutral-point side endof each phase coil, a neutral wire (not shown) that includes the samerectangular wire as that of the coil conductor 113 is connected usingsubstantially the same method as that of interconnecting the coilconductors 113. At a lateral end opposite to the neutral-point side endof each phase coil, a lead wire (not shown) that includes the samerectangular wire as that of the coil conductor 113 is connected usingsubstantially the same method as that of interconnecting the coilconductors 113. These wire connections make it possible to construct astator coil 112 based on distributed double-layer wave winding around asegment conductor, and to electrically connect the stator coil 112 tothe power module 410 (power converter) of the inverter unit 400 via thelead wire.

The neutral wire, together with the coil conductor 113, is inserted fromone axial lateral end of the stator core 111 (i.e., the insertion end ofthe second formed conductor 118), into the slot 111 b, and then at theother axial lateral end of the stator core 111 (i.e., an end opposite tothe insertion end of the second formed conductor 118), connected to theconnection of the coil conductor 113 that is equivalent to theneutral-point side end of each phase coil.

The lead wire is connected at one axial lateral end of the stator core111 (i.e., the insertion end of the second formed conductor 118) to theconnection of the coil conductor that is equivalent to an end oppositeto the neutral-point side end of each phase coil, and pulled from theother axial lateral end of the stator core 111 (i.e., the end oppositeto the insertion end of the second formed conductor 118) outward to oneaxial lateral end of the stator core 111 (i.e., the insertion end of thesecond formed conductor 118).

While the present embodiment has been described taking resistancebrazing as an example in connecting the connections 113 j, 113 k, otherconnecting methods such as TIG welding or silver brazing may be usedinstead.

In addition, although omitted from the drawings, slot-insulating paperfor providing electrical insulation between the stator core 111 and thestator coil 112 is provided in the present embodiment, between the slot111 b and the coil conductor 113. The slot-insulating paper is insertedinto the slot 111 b before the coil conductor 113 is inserted into theslot 111 b.

Furthermore, while an example in which, at one axial lateral end of thestator core 111 (i.e., the insertion end -of the second formed conductor118), the crossover side portion 113 f is disposed at the depthwisebottom side of the slot 111 b (i.e., an outside-diametral side of orexternally to the stator core 111) with respect to the crossover sideportion 113 e is taken has been described in the present embodiment, thecrossover side portion 113 f may be disposed at the depthwise open sideof the slot 111 b (i.e., an inside-diametral side of or internally tothe stator core 111).

Furthermore, the foregoing configuration of the stator 110 can also beapplied to the stator of the power generator 9 for the vehicle-mountedauxiliary devices or to the stator 210 of the dedicated electric powergenerator for driving.

According to the present embodiment, since the plurality of coilconductors 113 each having a crossover-side coil end 113 c that is aclosed end, and a connecting-side coil end 113 d that is an open end,are formed from a no-end rectangular conductor 116, that is, onecontinuous rectangular conductor 116, the stator coil 112 can beconstructed by inserting the plurality of coil conductors 113 from oneaxial lateral end of the stator core 111 into two spaced slots 111 b andthen connecting the plurality of coil conductors 113 at the other axiallateral end of the stator core 111. The number of man-hours needed tomount windings on the stator core 111, therefore, can be reduced incomparison with that of a stator coil constructed by inserting aplurality of coil conductors (half-coil conductors) from both axial endsof a stator core into a plurality of slots and then connecting theplurality of coil conductors at both axial ends of the stator core.Thus, according to the present embodiment, working efficiency associatedwith the mounting of windings can be improved.

Additionally, according to the present embodiment, since the openingangle θ1 of the crossover side of the crossover side portion 113 e withrespect to one axial lateral edge of the stator core 111 is larger thanthe opening angle θ2 of the crossover side of the crossover side portion113 f with respect to the same edge of the stator core 111, pointcontact between the crossover side portion 113 e of the crossover-sidecoil end can be made less prone to occur during the mounting of windingson the stator core 111.

More specifically, since the crossover side portion 113 e is rectilinearand since θ1 is 90 degrees, which is larger than the angle θ2 smallerthan 45 degrees, a bend (twist) is not formed between the crossover sideportion 113 e and the side portion 113 a, and when a coil conductor 113is inserted into two spaced slots 111 b and as shown in FIG. 7, when theside portion 113 a is pulled towards the connecting-side coil end 113 d(in a direction of an arrow) during the forming of the connecting-sidecoil end 113 d, it is possible to prevent the crossover side portion 113e of the crossover-side coil end 113 c from coming into point contactwith the stator core 111. Thus, according to the present embodiment, itis possible to reduce insulation damage (insulation defect) that thecrossover side portion 113 e of the crossover-side coil end 113 c maysuffer in case of this crossover side portion 113 e coming into pointcontact with the stator core 111.

Moreover, according to the present embodiment, since management of pointcontact of the crossover side portion 113 e of the crossover-side coilend 113 c with respect to the stator core 111 can be omitted, managementof point contact of the coil conductor 113 with the stator core 111needs only to be conducted, from the outer surface side of the statorcore 111 (i.e., the depthwise bottom side (upper-layer side) of the slot111 b) at a place enclosed in a dotted-line box, near the crossover-sidecoil end 113 c, in order to check for point contact with the stator core111 due to bending (twisting) between the crossover side portion 113 fand the side portion 113 b. Consequently, the management of pointcontact of the coil conductor 113 with the stator core 111 can befacilitated. According to the present embodiment, therefore, when pointcontact with the stator core 111 due to bending (twisting) between thecrossover side portion 113 f and the side portion 113 b is avoided,working efficiency associated with the mounting of windings on thestator core 111 is not reduced because of the above management of pointcontact.

For the above reasons, according to the present embodiment, it ispossible, while improving working efficiency associated with themounting of windings on the stator core 111, to improve the insulatingperformance of the stator core 111 and hence the fabricability andreliability of the motor 100.

In addition, according to the present embodiment, since the crossoverside portion 113 e of a large opening angle with respect to one axialedge of the stator core 111 is disposed at the inside-diametral sidethereof (i.e., the depthwise open side (lower layer) of the slot 111 b),a clearance between adjacent crossover side portions 113 e in thecrossover direction can be made larger than a clearance between theadjacent crossover side portions 113 f in the crossover direction thatare disposed at the outside-diametral side of the stator core 111 (i.e.,the depthwise open bottom side (upper layer) of the slot 111 b). Morespecifically, since the opening angle of each crossover side portion 113e is 90 degrees, the clearance between adjacent crossover side portions113 e in the crossover direction is set to be maximized. Because ofthis, according to the present embodiment, the clearance betweenadjacent crossover side portions 113 e in the crossover direction is notmade dependent upon height of the crossover-side coil end 113 c of thecoil conductor 113 (i.e., axial length from one axial edge of the statorcore 111 to a proximal end of the longest protruding portion facing theside of the bent-over portion 113 g that is opposite to the stator core111). According to the present embodiment, therefore, the height of thecrossover-side coil end 113 c can be easily managed by defining theclearance between the adjacent crossover side portions 113 f in thecrossover direction that are arranged at the outside-diametral side ofthe stator core 111. This managing method improves quality of the coilconductor 113, compared with managing the height of the crossover-sidecoil end 113 c by defining the clearance between adjacent crossover sideportions 113 e in the crossover direction. According to the presentembodiment that allows the quality of the coil conductor 113 to beimproved in this way, even if a bend (twist) in the coil conductor 113is brought close to one axial edge of the stator core 111 in order toreduce the height of the crossover-side coil end 113 c, point contactwith the stator core 111 due to the bend (twist) in the coil conductor113 can be reliably avoided and insulation damage to (insulation defectsin) the coil conductor 113 due to the point contact can be reduced.

Furthermore, according to the present embodiment, insulation is disposedin the clearance between adjacent crossover side portions 113 f in thecrossover direction by insertion or coating to improve dielectricstrength against an operating voltage, so the clearance between adjacentcrossover side portions 113 f in the crossover direction can be madeeven smaller and the height of the crossover-side coil end 113 c can befurther reduced.

Furthermore, according to the present embodiment, the rectilinear shapeof each crossover side portion 113 e makes it possible to reduce theamount of heat that the stator coil 112 generates. That is to say, ifforming causes a bend (twist) in the coil conductor 113, since thecorresponding portion becomes longer than other portions and hencedecreases in cross-sectional area, resistance increases above that ofother portions and the amount of heat increases above that of otherportions. According to the present embodiment, however, since there isno bend (twist) between the crossover side portion 113 e and the sideportion 113 a, the amount of heat that the stator coil 112 generates canbe correspondingly reduced.

Furthermore, according to the present embodiment, since the crossoverside portion 113 f is disposed at the outside-diametral side of thestator core 111 (i.e., the depthwise open bottom end (upper layer) ofthe slot 111 b), the bend (twist) between the crossover side portion 113e and the side portion 113 a, that is, the portion that is higher thanany other portions in resistance and in the amount of heat occurring canbe brought close to the aluminum-made first housing 101 excellent inheat-releasing property, and the heat stemming from the correspondingportion can be transmitted to the first housing 101 efficiently andreleased to the outside of the motor 100. According to the presentembodiment, therefore, it is possible to improve cooling performance ofthe stator coil 112 and reduce increases in the internal temperature ofthe motor 100.

If the rotor 120 has a cooling fan, disposing the crossover side portion113 f at the inside-diametral side of the stator core 111 (i.e., thedepthwise open end (lower layer) of the slot 111 b) makes efficientcooling of the bend (twist) between the side portion 113 b and thecrossover side portion 113 f possible by assigning a flow of cooling airof a relatively low temperature.

Furthermore, according to the present embodiment, since the crossoverside portion 113 e is formed into a rectilinear shape and only thecrossover side portion 113 e has a bend (twist), the coil conductor 113can be formed into a simple structure, not a complex structure. Becauseof this, according to the present embodiment, dies that are used to formthe coil conductor 113 can also be formed into a simple structure, andthe number of man-hours required for the forming of the coil conductor113 can be reduced. According to the present embodiment, therefore,manufacturing costs for the motor 100 can be reduced and the motor 100itself can be easily manufactured.

Furthermore, according to the present embodiment, since the openingangle of the crossover side portion 113 e with respect to one axiallateral edge of the stator core 111 is 90 degrees that is larger thanthe opening angle of the crossover side portion 113 f, and since thecrossover side portion 113 e has a rectilinear shape, it is possible,during the forming of the connecting-side coil end 113 d, to pull in theside portion 113 a towards the connecting-side coil end 113 d, and thebend (twist) formed between the side portion 113 a and the crossoverside portion 113 h can be away from the other axial lateral edge of thestator core 111. According to the present embodiment, therefore, pointcontact between the stator core 111 and the bend (twist) formed betweenthe side portion 113 a and the crossover side portion 113 h can bereliably avoided and insulation damage to (insulation defects in) thecoil conductor 113 due to point contact of the particular bent (twisted)portion can be reduced.

Furthermore, according to the present embodiment, since the crossoverside portion 113 e is formed into a rectilinear shape and only thecrossover side portion 113 f has a bend (twist), variations in an axialposition of the crossover side portion 113 e and in an axial position ofthe bend (twist) provided in the crossover side portion 113 f can beremoved. This, in turn, makes it possible, according to the presentembodiment, to remove variations in the height of the crossover-sidecoil end 113 c (i.e., axial length from one axial edge of the statorcore 111 to the proximal end of the longest protruding portion facingthe side of the bent-over portion 113 g that is opposite to the statorcore 111). According to the present embodiment, therefore, the height ofthe crossover-side coil end 113 c can be correspondingly reduced onceany variations in the height of the crossover-side coil end 113 c havebeen removed.

Furthermore, according to the present embodiment, since the crossoverside portion 113 e is formed into a rectilinear shape and only thecrossover side portion 113 f has a bend (twist), the shapes of theconductors at both sides of the bent-over portion 113 g can be madedifferent from each other. Thus, according to the present embodiment,when the second formed conductor 118 is inserted into two spaced slots111 b, relational adequacy between the side portions of the secondformed conductor 118 inserted and the slots 111 b into which theconductor is inserted can be easily confirmed and mistakes in theinsertion of the second formed conductor 118 into the two spaced slots111 b can be reduced.

Furthermore, according to the present embodiment, since the openingangle θ1 of the crossover side of the crossover side portion 113 e withrespect to one axial edge of the stator core 111 is 90 degrees that islarger than the opening angle θ2 of the crossover side of the crossoverside portion 113 f with respect to the same edge of the stator core 111,after all coil conductors 113 have been mounted on the stator core 111,the lead wire, the neutral wire, and other coil conductors of dissimilarshapes can be mounted on the stator core 111. For this reason, accordingto the present embodiment, it is possible to improve the mountability ofwindings on the stator core 111 and improve the fabricability of themotor 100.

Moreover, according to the present embodiment, since the opening angleθ1 of the crossover side of the crossover side portion 113 e withrespect to one axial edge of the stator core 111 is larger than theopening angle θ2 of the crossover side of the crossover side portion 113f with respect to the same edge of the stator core 111, the length ofthe crossover side portion 113 f from one end of the side portion 113 b(i.e., the opposite end with respect to the connection 113 k) to thebent-over portion 113 g can be made greater than the length of thecrossover side portion 113 e from one end of the side portion 113 a(i.e., the opposite end with respect to the connection 113 j) to thebent-over portion 113 g. This makes it possible, according to thepresent embodiment, to change the crossover side portions 113 e, 113 fin resonance frequency. According to the present embodiment, therefore,a point of resonance with the electromagnetic noise stemming from thestator core 111 can be distributed into multiple form and a peak levelof the electromagnetic noise can be reduced.

That is to say, as shown in FIG. 8B, in a comparative example where,with substantially an equal value assigned between an opening angle θ3of a crossover side of a crossover side portion 910 a with respect toone axial edge of a stator core 900, and an opening angle θ4 of acrossover side of a crossover side portion 910 b with respect to thesame edge of the stator core 900, length of the crossover side portion910 b from one lateral end of one of the side portions to a bent-overportion 910 c is substantially equal to length of the crossover sideportion 910 a from one lateral end of the other side portion to thebent-over portion 910 c, the crossover side portions 910 a and 910 b aresubstantially the same in resonance frequency. The number of resonancepoints overlapping in frequency of the electromagnetic noise stemmingfrom the stator core 900, therefore, is 1 in the comparative example.This results in a peak electromagnetic noise level increasing in thecomparative example.

In contrast to this, in the present embodiment, since as shown in FIG.8A, the crossover side portions 113 e and 113 f differ in resonancefrequency, the resonance point that overlaps a frequency of theelectromagnetic noise stemming from the stator core 111 is distributedinto two parts and the peak level of the electromagnetic noise cantherefore be reduced.

Second Embodiment

A second embodiment of the present embodiment will be described inaccordance with FIGS. 9 to 11.

The present embodiment is an improvement on the first embodiment, and inthe present embodiment, the crossover side portions of theconnecting-side coil end 113 d are formed similarly to those of thecrossover-side coil end 113 c. That is to say, the crossover sideportion 113 i is a rectilinear portion extending rectilinearly from theother lateral end of the side portion 113 b (i.e., the side opposite tothe crossover side portion 113 f), towards the side opposite to thecrossover side portion 113 f. The crossover side portion 113 h is aninclined portion extending from the other lateral end of the sideportion 113 a (i.e., the end opposite to the crossover side portion 113e), in a direction of the end opposite to the crossover side portion 113e (i.e., the direction in which the crossover side portion axially isaway from the stator core 111), while the same extends in a directionopposite to the crossover direction of the crossover-side coil end 113c.

In the present embodiment, line segment 116 b in FIG. 9A serves as asegment that longitudinally bisects two faces 116 a of a smaller area ofall four faces parallel to the central axis of the rectangular conductor116. Because of this, when the rectangular conductor 116 is bent, thelengths of the side portions 117 a and 117 b of the first formed element117 become equal as shown in FIG. 9B. In addition, in the presentembodiment, when the end of the side portion 117 a that faces thebent-over portion 117 c is bent with the segments 117 d, 117 e asbending axes, the length of the side portion 118 a of the second formedelement 118 becomes greater than the length of the side portion 118 b,as shown in FIG. 9C.

The connecting-side coil end 113 d is formed so that the opening angle(90 degrees) of the crossover side of the crossover side portion 113 iwith respect to an end face of the other axial end of the stator core111 (i.e., the side opposite to the insertion end of the second formedconductor 118 with respect to the slots 111 b) is larger than theopening angle (smaller than 45 degrees) of the crossover side of thecrossover side portion 113 h with respect to the same end of the statorcore 111.

Additionally, because of the angular relationship between the crossoverside portions 113 h, 113 i, the length of the crossover side portion 113h from the other lateral end of the side portion 113 a (i.e., theopposite end with respect to the crossover side portion 113 e) to theconnection 113 j is greater than the length of the crossover sideportion 113 i from the other lateral end of the side portion 113 b(i.e., the opposite end with respect to the crossover side portion 113f) to the connection 113 k.

Furthermore, because of the angular relationship between the crossoverside portions 113 h, 113 i, the element to be connected that includesthe connections 113 j, 113 k in the circumferential direction of thestator core 111 (i.e., the crossover direction of the crossover-sidecoil end 113 d) is formed to be disposed on an extension line of theside portion 113 b, with an offset thereto, compared with anintermediate position of the pitch of two slots spaced according to aparticular rotating pole pitch as shown in FIG. 10. Also, the layoutposition of the bent-over portion 113 g in the circumferential directionof the stator core 111 (i.e., the crossover direction of thecrossover-side coil end 113 c) is the same as the layout position of theabove element to be connected, in the circumferential direction of thestator core 111 (i.e., the crossover direction of the connecting-sidecoil end 113 d).

The clearance between crossover side portions 113 i adjacent to eachother in the crossover direction is, as shown in FIG. 10, equal to theclearance between crossover side portions 113 e adjacent to each otherin the crossover direction. In addition, as shown in FIG. 10, theclearance between the adjacent crossover side portions 113 i in thecrossover direction, and the clearance between the adjacent crossoverside portions 113 e in the crossover direction are larger than theclearance between crossover side portions 113 h adjacent to each otherin the crossover direction, and the clearance between crossover sideportions 113 f adjacent to each other in the crossover direction.

At the other axial end of the stator core 111 (i.e., the side oppositeto the insertion end of the second formed conductor 118), the crossoverside portion 113 h is disposed at the depthwise open side of the slots111 b (i.e., the inside-diametral side of the stator core 111 orinternally thereto) with respect to the crossover side portion 113 i,and this relationship in layout position is a reciprocal of that of thecrossover side portions 113 e, 113 f of the crossover-side coil end 113c. Accordingly, reversal of the layout positions of the crossover sideportions 113 e, 113 f also reverses the layout positions of thecrossover side portions 113 h, 113 i.

If the crossover side portion at one lateral end of the side portion 113a is rectilinear and the crossover side portion at one lateral end ofthe side portion 113 b is oblique, the crossover side portion at theother lateral end of the side portion 113 a is oblique and the crossoverside portion at the other lateral end of the side portion 113 b isrectilinear.

Other structural parts are substantially the same as in the firstembodiment, and description of the other structural aspects is omitted.

According to the present embodiment, it is possible to achievesubstantially the same advantageous effects as obtainable in the firstembodiment, and since the crossover side portion 113 i is formed into arectilinear shape and since the bend (twist) in the connecting-side coilend 113 d is formed only on the crossover side portion 113 h, a bend(twist) is not formed between the crossover side portions 113 i and 113b and it is consequently possible to prevent the crossover side portion113 i of the connecting-side coil end 113 d from coming into pointcontact with the stator core 111. In addition, as shown in FIG. 11, whenthe connecting-side coil end 113 d of the coil conductor 113 is formed,although the side portion 113 a is pulled towards the connecting-sidecoil end 113 d (i.e., in a direction of an arrow), the side portion 113b is not pulled towards the connecting-side coil end 113 d. Because ofthis, according to the present embodiment, the bend (twist) between thecrossover side portion 113 f and the side portion 113 b can be preventedfrom coming into point contact with the stator core 111. This, in turn,makes it possible, according to the present embodiment, to avoid pointcontact of the bend (twist) in coil conductor 113 with respect to thestator core 111, and to further reduce insulation damage to (insulationdefects in) the coil conductor 113 due to the point contact.

1. An electric machine comprising: a core having a plurality of slots;and a winding including a plurality of unit windings having a conductorside portion, a crossover-side conductor end and a connecting-sideconductor end, wherein the conductor side portion is stored in any twoof the slots that are spaced from each other, the crossover-sideconductor end is guided from one end of the core outside the slots andcrossing over from one of the two slots to the other in order to linkthe two conductor side portions, and the connecting-side conductor endhaving two conductor-connecting ends, and being guided from the otherend of the core outside the slots, and the conductor side portion, thecrossover-side conductor end and the connecting-side conductor end areinterconnected each other to construct the winding; wherein theplurality of unit windings are each formed under a no-end state at anyportions from one of the two conductor-connecting ends to the other; andthe crossover-side conductor end includes a first conductor lead-outportion guided outward from one of the two slots and extending from oneend of the core, in a direction where the lead-out portion is away fromthe core end, a second conductor lead-out portion guided outward fromthe other of the two slots and extending from one end of the core, in adirection where the lead-out portion is away from the core end, and abent-over conductor portion linking the first and second conductorlead-out portions and causing the extending directions thereof to changefrom one of the first and second lead-out portions to the other; whereinan angle θ1 of the first conductor lead-out portion in the crossingdirection thereof with respect to an end face of one end of the core isgreater than an angle θ2 of the second conductor lead-out portion in thecrossing direction thereof with respect to the same end face of thecore.
 2. The electric machine according to claim 1, wherein: length ofthe second conductor lead-out portion extending from the end face of oneend of the core to the bent-over conductor portion is greater thanlength of the first conductor lead-out portion extending from the sameend face of the core to the bent-over conductor portion.
 3. The electricmachine according to claim 1, wherein: the bent-over conductor portionis disposed with an offset from an intermediate position of a pitch ofthe two slots to the first conductor lead-out portion.
 4. The electricmachine according to claim 1, wherein: the second conductor lead-outportion is disposed at a depthwise bottom side of the slots with respectto the first conductor lead-out portion.
 5. The electric machineaccording to claim 1, wherein: the second conductor lead-out portion isdisposed at an opposite side of a depthwise bottom side of the slotswith respect to the first conductor lead-out portion.
 6. The electricmachine according to claim 1, wherein: a clearance between the firstconductor lead-out portions adjacent to each other in the crossoverdirection is greater than a clearance formed between the secondconductor lead-out portions adjacent to each other in the crossoverdirection.
 7. The electric machine according to claim 6, wherein: aninsulating member is disposed in the clearance between the secondconductor lead-out portions adjacent to each other in the crossoverdirection.
 8. The electric machine according to claim 1, wherein: theconnecting-side conductor end includes a third conductor lead-outportion guided outward from one of the two slots, extending in adirection where the lead-out portion is away from the other end of thecore, and having one of the conductor-connecting ends formed at aproximal end, and a fourth conductor lead-out portion guided outwardfrom the other of the two slots, extending in a direction where thelead-out portion is away from the other end of the core, and having oneof the conductor-connecting ends formed at a proximal end; wherein thethird and fourth conductor lead-out portions are bent in directionsopposite to the respective crossing directions, and the twoconductor-connecting ends each overlap conductor-connecting ends of theother unit windings.
 9. The electric machine according to claim 8,wherein: a connection at which the conductor-connecting ends of twodifferent unit windings overlap is disposed at a position different fromthat of the bent-over conductor portion.
 10. The electric machineaccording to claim 9, wherein: the connection is disposed at anintermediate position of a pitch of the two slots.
 11. The electricmachine according to claim 8, wherein: of the clearances defined betweenthe first conductor lead-out portions adjacent to each other in thecrossover direction, between the second conductor lead-out portionsadjacent to each other in the crossover direction, between the thirdconductor lead-out portions adjacent to each other in the crossoverdirection, between the fourth conductor lead-out portions adjacent toeach other in the crossover direction, the clearance defined between thefirst conductor lead-out portions is the largest and the clearancedefined between the second conductor lead-out portions is the smallest.12. The electric machine according to claim 1, wherein: theconnecting-side conductor end includes a third conductor lead-outportion guided outward from one of the two slots, extending in adirection where the lead-out portion is away from the other end of thecore, and having one of the conductor-connecting ends formed at aproximal end, and a fourth conductor lead-out portion guided outwardfrom the other of the two slots, extending in a direction where thelead-out portion is away from the other end of the core, and having oneof the conductor-connecting ends formed at a proximal end; wherein anangle θ3 of an opposite side of the crossover side of the thirdconductor lead-out portion with respect to the other end face of the endof the core end is smaller than an angle θ4 of an opposite side of thecrossover side of the fourth conductor lead-out portion with respect tothe other end face of the core end.
 13. The electric machine accordingto claim 12, wherein: length of the third conductor lead-out portionfrom the other edge of the core end to the conductor-connecting end isgreater than length of the fourth conductor lead-out portion from thethe edge of the core end to the conductor-connecting end.
 14. Theelectric machine according to claim 12, wherein: theconductor-connecting end is disposed at the same position as that of thebent-over conductor portion.
 15. The electric machine according to claim12, wherein: when the second conductor lead-out portion is disposed at adepthwise bottom side of the slots with respect to the first conductorlead-out portion, the third conductor lead-out portion is disposed at anopposite side of the depthwise bottom side of the slots with respect tothe fourth conductor lead-out portion; and if the second conductorlead-out portion is disposed at the opposite side of the depthwisebottom side of the slots with respect to the first conductor lead-outportion, the third conductor lead-out portion is disposed at thedepthwise bottom side of the slots with respect to the fourth conductorlead-out portion.
 16. The electric machine according to claim 12,wherein: a clearance defined between the third conductor lead-outportions adjacent to each other in the crossover direction is smallerthan a clearance defined between the fourth conductor lead-out portionsadjacent to each other in the crossover direction.
 17. The electricmachine according to claim 16, wherein: an insulating member is disposedin the clearance between the adjacent third conductor lead-out portionsin the crossover direction.
 18. The electric machine according to claim12, wherein: the third conductor lead-out portion is bent in a directionopposite to the crossover direction; the fourth conductor lead-outportion extends rectilinearly from the other end of the core; theconductor-connecting end of the third conductor lead-out portion isconnected with the conductor-connecting end of the fourth conductorlead-out portion of any other unit winding with them overlapped; and theconductor-connecting end of the fourth conductor lead-out portion isconnected with the conductor-connecting end of the third conductorlead-out portion of any other unit winding with them overlapped.
 19. Theelectric machine according to claim 1, wherein: the winding conductorconstituting the unit winding is of a rectangular cross-sectional shape.20. An electric machine comprising: a core having a plurality of slots;and a core having a plurality of slots; and a winding including aplurality of unit windings having a conductor side portion, acrossover-side conductor end and a connecting-side conductor end,wherein the conductor side portion is stored in any two of the slotsthat are spaced from each other, the crossover-side conductor end isguided from one end of the core outside the slots and crossing over fromone of the two slots to the other in order to link the two conductorside portions, and the connecting-side conductor end having twoconductor-connecting ends, and being guided from the other end of thecore outside the slots, and the conductor side portion, thecrossover-side conductor end and the connecting-side conductor end areinterconnected each other to construct the winding; wherein: theplurality of unit windings are each formed under a no-end state at anyportions from one of the two conductor-connecting ends to the other; andthe crossover-side conductor end includes a first conductor lead-outportion guided outward from one of the two slots and extending from oneend of the core, in a direction where the lead-out portion is away fromthe core end, a second conductor lead-out portion guided outward fromthe other of the two slots and extending from one end of the core, in adirection where the lead-out portion is away from the core end, and abent-over conductor portion linking the first and second conductorlead-out portions and causing the extending directions thereof to changefrom one of the first and second lead-out portions to the other; whereinlength of the second conductor lead-out portion extending from an endface of one end of the core end to the bent-over conductor portion isgreater than length of the first conductor lead-out portion extendingfrom the same end face of the end to the bent-over conductor portion.21. An electric machine comprising: a core having a plurality of slots;and a winding including a plurality of unit windings having a conductorside portion, a crossover-side conductor end and a connecting-sideconductor end, wherein the conductor side portion is stored in any twoof the slots that are spaced from each other, the crossover-sideconductor end is guided from one end of the core outside the slots andcrossing over from one of the two slots to the other in order to linkthe two conductor side portions, and the connecting-side conductor endhaving two conductor-connecting ends, and being guided from the otherend of the core outside the slots, and the conductor side portion, thecrossover-side conductor end and the connecting-side conductor end areinterconnected each other to construct the winding; wherein: theplurality of unit windings are each formed under a no-end state at anyportions from one of the two conductor-connecting ends to the other; andthe crossover-side conductor end includes a first conductor lead-outportion guided outward from one of the two slots and extending from oneend of the core, in a direction where the lead-out portion is away fromthe core end, a second conductor lead-out portion guided outward fromthe other of the two slots, then bent, and extending towards the firstconductor lead-out portion so as to be away from one end of the core,and a bent-over conductor portion linking the first and second conductorlead-out portions and causing the extending directions thereof to changefrom one of the first and second lead-out portions to the other, thebent-over conductor portion being disposed with an offset towards thefirst conductor lead-out portion with respect to an intermediateposition of a pitch of the two slots.
 22. A process for manufacturing anelectric machine, the process comprising: a forming step that includesthe substeps of preparing a plurality of winding conductors, and thenbending each of the plural winding conductors into two pieces to form aplurality of first formed conductor constructed of two side portionsextending in line in one direction, and a bent-over portion linking theside portions at one end of each side portion in a longitudinaldirection thereof, in order that a stepped portion based on a depthwisedimension of each of a plurality of slots formed in a core is formedbetween the side portions of the first formed conductor, spreading oneside portion of the first formed conductor away from the other sideportion thereof to form a plurality of second formed conductors eachconstructed of two side portions extending in one direction and having adifference in surface height, a rectilinear portion extendingrectilinearly at one longitudinal end of each of the side portions, acrossover portion inclusive of an oblique portion extending obliquelywith respect to each of the side portions, and of a bent-over portionlinking the rectilinear portion and the oblique portion, and an open endformed at the other longitudinal end of each of the side portions,inserting each of the plural second formed conductors from one end ofthe core into the two spaced slots such that one of the side portions ofeach second formed conductor is disposed at one depthwise side of one ofthe two spaced slots and such that the other of the side portions ofeach second formed conductor is disposed at the other depthwise side ofthe other of the two spaced slots, and forming each of side portionswhich protrude from the other end of the core to an external portion ofeach of the slots, such that each side portion is bent in a directionopposite to a crossover direction of the crossover portion and such thata proximal end of the side portion overlaps, of all side portionproximal ends of the other second formed conductors, only a proximal endof a side portion different in depthwise layout position on the slot;and after execution of forming in the forming step, connecting theoverlapping ends to each other.
 23. A process for manufacturing anelectric machine, the process comprising: a forming step that includesthe substeps of after making a plurality of winding conductors ready foruse, bending each of the plural winding conductors into two pieces toform a plurality of first formed conductor constructed of two sideportions extending in line in one direction, and a bent-over portionlinking the side portions at one end of each side portion in alongitudinal direction thereof, in order that a stepped portion based ona depthwise dimension of each of a plurality of slots formed in a coreis formed between the side portions of the first formed conductor,spreading one side portion of the first formed conductor away from theother side portion thereof to form a plurality of second formedconductors each constructed of two side portions extending in onedirection and having a difference in surface height, a rectilinearportion extending rectilinearly at one longitudinal end of each of theside portions, a crossover portion inclusive of an oblique portionextending obliquely with respect to each of the side portions, and of abent-over portion linking the rectilinear portion and the obliqueportion, and an open end formed at the other longitudinal end of each ofthe side portions, inserting each of the plural second formed conductorsfrom one end of the core into the two spaced slots such that one of theside portions of each second formed conductor is disposed at onedepthwise side of one of the two spaced slots and such that the other ofthe side portions of each second formed conductor is disposed at theother depthwise side of the other of the two spaced slots, and formingside portions which protrude from the other end of the core to anexternal portion of each of the slots, by, while one of the protrudingside portions rectilinearly is extended, causing a proximal end of therectilinear side portion to overlap the other proximal end of the sideportion of any other of the second formed conductors, and bending theother of the protruding side portions in a direction opposite to acrossover direction of the crossover portion such that a proximal end ofthe bent side portion overlaps a proximal end of one side portion of anyother of the second formed conductors; and after execution of forming inthe forming step, connecting the overlapping ends to each other.